Litton C.W., . Reynolds D.C., Collins T.C. Zinc Oxide Materials for Electronic and Optoelectronic Device Applications

Подождите немного. Документ загружается.

nonaxial type of centers. The hybridization also varies, being closer to sp

in the case of the

nonaxial centers while the orbital is much more p-like for the axial center.

This leads to a distorted center in which the sodium atom is shifted from the regular Zn

position. A geometrical interpretation of the bond angle gives a value of r

nax

¼2.05 A



for

the nonaxial case if the shift is along the norm al bond direction. The normal length of this

bond is 1.97 A



. One can also ﬁnd an estimate for the bond length r

in the axial case by

considering that b reﬂects a dipole-type of state. The lengths in both cases should relate to

each other like the sixth root of the relationship of the corresponding anisotropic hyperﬁne

interaction parameters:

nax

¼ðb

nax

1=6

ð6:13Þ

Using this equation one ﬁnds a bond length r

¼2.2 A



, that means the bond is longer in

the axial case (which is parallel c).

The g-tensor allows an estimate of the energy separation between the acceptor state and

the valence band. The g-shift is related to this energy separation and the spin-orbit

coupling of the atom that contributes to the state.

[113]

The spin-orbit coupling of sodium is

close to zero, therefore the contribution comes from the oxygen ligand. Using the

admixture factor h

one obtains for the energy separation:

DE ¼2lð1h

Þ=ðg

g

Þð6:14Þ

The values of 730 meV (axial centers) and 640 meV (nonaxial centers) are in agreement

with the results of the photoluminescence measurements (see below). A detailed study of

the EPR temperature dependence conﬁrms these results on the energy barrier between both

types of centers.

[119]

The sodium-doped samples showed a strong luminescence line in the excitonic range

followed by a broad, unstructured luminescence band in the visible spect ral range (see

Figure 6.20). This b and can be decompos ed into two Gaussian bands with peak energies of

2.48 eV (marked as II) and 2.15 eV (marked as I). Temperature-dependent measure-

ments

[120]

of the half-width of band I revealed a Huang–Rhys factor S of about 16 1.5

and participation of local phonons of h¯ v ¼(45 5) meV. This leads to a (hypothet ical)

zero phonon transition at 2.87 eV (peak position at 2.15 eV plus Sh¯ v), that is, 580 meV

below the band gap energy in fair agreement with the data analysis of the g-anisoptropy.

The corresponding values for the Li acceptor are: peak energy at 2.1 eV, a Huang–Rhys

factor S of about 13 1 and participation of local phonons of h¯ v ¼(50 5) meV, zero

phonon transition at 2.75 eV (peak position plus Sh¯ v), that is, 700 meV below the band gap

energy. The values of 580 and 700 meV for the Na and Li acceptors are equivalent to the

acceptor binding energies since the recombinations investigated in ODMR were of the

shallow donor to deep acceptor type.

A direct correlation to the Na related photoluminescence band was obtained by ODMR

excitation spectroscopy (Figure 6.20).

[120]

The sample shows overlapping broad emission

bands in the visible; the Na related magnetic resonance signals were detected only on the

deeper lying emission I, while emission II showed no magnetic resonance response.

The intense research to ﬁnd suitable acceptors for the p-type dopin g has led to a

reinvestigation of the behavior of the group-I elements over recent years. While in the old

162 Spectral Identiﬁcation of Impurities and Native Defects in ZnO

work bulk crystals and high diffusion temperatures were used, now moderate temperatures

(G800



C) and epitaxial ﬁlms came into play. Evidence for a Li related center causing a

DAP recombination with a ZPL at 3.05 eV was found by Sann et al.

[121]

Figure 6.21 shows a low-temperature photoluminescence measurement of a sample

where Li was introduced during growth. A newly observed luminescence starts at around

3.1 eV, and shows pronounced coupling to longitudinal optical (LO) phonons separated by

3.43.23.02.82.62.42.22.01.8

4 K

HeCd

PL-intensity (arb. units)

Ener

y (eV)

Figure 6.20 Luminescence spectrum of a Na-doped ZnO single crystal showing the band edge

excitonic recombinations and the deep centre emission decomposed into two Gaussian

contributions. The ODMR spectrum of the Na acceptor is only detected on band I. Reprinted

with permission from F.H. Leiter, Thesis, Gieben, 2002

3.43.33.23.13.02.92.8

DA-LO

DA-2LO

x10

PL-intensity (arb. units)

Energy (eV)

Figure 6.21 Luminescence spectrum at T ¼4.2 K of a Li-doped ZnO epitaxial ﬁlm grown by

CVD. The position of the DAP band at 3.05 eV and its LO replica are indicated. Reprinted from

J. Sann, A. Hofstaetter, D. Pﬁsterer, J. Stehr, and B.K. Meyer, phys. stat. sol.(c) 3, 952.

Magnetic Resonance Investigations 163

72 meV. The shape is typical for DAP recombination. The coupling strength given by the

Huang–Rhys factor S is estimated from the Poisson distribution I ¼I

/n! where n ¼0, 1,

2, ... and I

is the intensity of the ﬁrst, the ZPL. For S one obtains a value of 0.35 0.05

which can be compared with the value of 0.55 0.05 obtained for the nitrogen acceptor

with a binding energy of 165 meV.

[66]

If we assume a value of 50 meV for the donor

binding energy, and neglect the coulombic interaction one obtains an acceptor binding

energy around 300 meV, and one may wonder why the phonon coupling strength is

so small.

In 1960 Lander

[122]

reported on the donor and acceptor properties of Li and gave

ﬁrst indications about the possible defe ct structure . He proposed the interplay between

interstitial Li donors and substitutional Li

acceptors. Lander

[122]

observed a decrease in

conductivity which was dependent on the oxygen pressure during doping and concluded

that for the realization of p-type ZnO:Li very high (and not achievable) oxygen pressures

were needed. The main reason for the conversion from n-type to high resistive ZnO:Li was

presented in the work of Zwingel.

[123]

He showed that the conductivity decreased in

inverse proportion to the square of the Li concentration. Only 1% of the total Li

concentration was effective in the compensation of the donors already present in the

crystal. He assumed equal concentrations for the interstitial Li donors and Li

acceptors

and postulated the existence of another Li acceptor, needed to model the reaction kinetics.

It should arise from the pairing of two Li centers. The luminescence/EPR investiga-

tions

[121]

do not allow to conclude whether one or two Li atoms are part of the 300 meV

acceptor. For the epitaxial ﬁlms Li and Na dopin g in all cases enhanced signiﬁcantly the

luminescence in the yellow spectral range (compared with undoped sample s where the Cu

emission with well resolved phonon structure is observed). This can be used as an

indication that also the deep Li (Na) acceptor was formed, and that there is a branching

ratio between the shallow and deep Li centers. A defect model of shallow Li with nearby H

donors was proposed.

[121]

A similar model was proposed by Halliburton et al.

[124]

based

on a combined investigation of the infrared absorption and magnetic reso nance.

Novel aspects on the group-I elements come from the synthesis of ZnO nanocrystals.

Here LiOH or NaOH are used as oxygen precursors and the materials are prepared at room

temperature. ENDOR investigations show that under such conditions Na and Li can exist

in interstitial positions thus being shallow donors. Together with the Li

acceptors charge

neutrality is obtained in the nanocrystals by this type of extrinsic-self-compensation

process.

[125]

The most crucial point for the future of ZnO as material for electronic and optoelec-

tronic devices is the ability to dope it reliable p-type and thus to ﬁnd an efﬁcient shallow

acceptor which is able to release holes in sufﬁcient concentration to the valence band.

Meanwhile, many doping techniques and various growth processes have been applied to

achieve this goal, however, with limited success. From the point of characterization by

means of magnetic resonance methods to our knowledge only information on two types of

species was obtained. One is the Zn vacancy and related defects, and the other one is

nitrogen. Nitrogen can be expected to occupy an oxygen site considering the small size

mismatch, and thus has the potential to be an acceptor. Indeed a nitrogen acceptor center

compatible was detected in EPR, originally in single crystals, later also in nitrogen-treated

ZnO powders.

[108,126]

Figure 6.22 shows the EPR signal of the nitrogen acceptor for

different orientations of the magnetic ﬁeld with respect to the c-axis of the ZnO crystal.

164 Spectral Identiﬁcation of Impurities and Native Defects in ZnO

The g-values are not what one expects for shallow effective-mass-type acceptors (see

Table 6.1 and Figure 6.23), also the observation of hyperﬁne interaction with the nitrogen

N ¼1 nuclear spin rules against a shallow center. Carlos et al.

[108]

remarked that the large

anisotropy in the hyperﬁne interaction suggests that a p-orbital (p-hole) is involved. From

Figure 6.22 The EPR signal of the N acceptor at selected orientations. Reprinted from W. E.

Carlos, E. R. Glaser, and D. C. Look, Magnetic resonance studies of ZnO , Physica B 308–310,

976. Copyright (2001) with permission from Elsevier

2.042.022.001.981.961.94

1.94

1.96

1.98

2.00

2.02

2.04

Zn - N

EM donors

⊥

Figure 6.23 Compilation of the g-values of shallow and deep defects in ZnO. The diagonal line

refers to isotropic g-values; the horizontal line is a guide for the eye

Magnetic Resonance Investigations 165

an atomic orbital analysis follows that the center has 96% p and 4% s character, and has a

4% localization of the nitrogen atom. It is obvious that from the spin Hamilton parameters

and their analysis one deals with a deep and not a shallow acceptor. Carlos et al.

[108]

pointed out the similarity to the deep states of As and P in ZnSe – a p-orbital on the

impurity atom which is Jahn–Teller distorted. While this is certainly correct one may

notice: As and P in ZnSe also introduce shallow effective-mass-type acceptor states, and

depending on the growth method and growth parameters (melt grown or low temperature

epitaxial growth, II/VI ratio, etc.) there can be preference which acceptor state is favored.

The shallow acceptor state introduced by nitrogen doping, by diffusion and implantation

(see above) obviously has so far escaped detection by magnetic resonance techniques.

Apart from this deep N



acceptor also mol ecular nitrogen (N



) acceptors were

found.

[127,128]

Studying the annealing behavior of these two N centers,

[127]

compensation

(probably by hydrogen) was noticed as well as the deactivation of the centers at

temperatures above 800



C. Here we also would like to draw attention to the work of

Aliev et al.

[129]

who obtained evidence that compensation of the nitrogen acceptors may

also happen via the pairing with zinc interstitials. Such defects models were also found in

ammonia-treated ZnO powder samples by Sann et al.

[130]

6.3.4 Intrinsic Acceptors

The ﬁrst information on Zn vacancies was obtained in the 1970s. Room temperature

electron- and neutron-irradiated samples were studied.

[131–133]

More recently the work of

Vlasenko and Watkins

[109]

revealed the creation and annealing behavior of V

by low

temperature electron irradiation. Frenkel pairs of the Zn vacancy with the Zn interstitial

were observed and the annealing stages below 170 K were related to the migration of the

Zn interstitials. In correlating these ODMR results to the photoluminescence bands present

in the material and comparing the results with the better studied case of ZnSe, the authors

obtained evidence that the Zn vacancy levels are at least 350 meV above the valence band

or even higher.

In summary, while the identiﬁcation of the impurities, dopants and intrinsic defects in

ZnO by magnetic resonance methods is in a good state there is a lack of data which relates

this information to electrical or optical properties of the material.

Note, the magnetic resonance data of the transition metal elements Sc.....Cu were not

considered in this chapter. They are defects in their own right and would demand an

independent compilation.

[134–139]

While they are common defects in ZnO bulk crystals

they play a minor role in thin ﬁlms relevant for optoelectronic applications. Using the same

argument, defects such as Mo

[140]

and Pb

[141]

in ZnO have not been reviewed.

References

[1] D.G. Thomas, J. Phys. Chem. Solids 15, 86 (1960).

[2] J.J. Hopﬁeld, J. Phys. Chem. Solids 15, 97 (1960).

[3] Y.S. Park. C.W. Litton, T.C. Collins and D.C. Reynolds, Phys. Rev. 143, 512 (1966).

[4] B. Segall, Phys. Rev. 163, 769 (1967).

[5] W.Y. Liang and A.D. Yoffe, Phys. Rev. Lett. 20, 59 (1968).

[6] K. H

€

ummer, Phys. Status Solidi. 56, 249 (1973).

166 Spectral Identiﬁcation of Impurities and Native Defects in ZnO

[7] M. Rosenzweig, Diploma thesis, TU Berlin, 1975.

[8] G. Blattner, G. Kurtze, G. Schmieder and C. Klingshirn, Phys. Rev. B 25, 7413 (1982).

[9] B.C. Reynolds, D.C. Look, B. Jogai, C.W. Litton, G. Cantwell and W.C. Harsch, Phys. Rev. B

60, 2340 (1999).

[10] B. Gil, Phys. Rev. B 64, 201310 (R) (2001); see also B. Gil, A. Lusson, V. Sallet, R. Triboulet

and P. Bigenwald, Jpn J. Appl. Phys. Lett. (to be published).

[11] W.L.R. Lambrecht, A.V. Rodina, S. Limpijumnong, B. Segall and B.K. Meyer, Phys. Rev. B

65, 075207 (2002).

[12] J. Gutowski, N. Presser and I. Broser, Phys. Rev. B 38, 9746 (1988).

[13] G. Blattner, C. Klingshirn, R. Helbig and R. Meinl, Phys. Status Solidi B 107, 105 (1981).

[14] P. Loose, M. Rosenzweig and M. W

€

ohlecke, Phys. Status Solidi B 75, 137 (1976).

[15] D.C. Reynolds, C.W. Litton and T.C. Collins, Phys. Rev. 140, A1726 (1965).

[16] D.C. Reynolds and T.C. Collins, Phys. Rev. 185, 1099 (1969).

[17] B.K. Meyer, H. Alves, D.M. Hofmann, W. Kriegseis, D. Forster, F. Bertram, J. Christen,

A. Hoffmann, M. Straßburg, M. Dworzak, U. Haboeck and A.V. Rodina, Phys. Status Solidi B

241, 231 (2004).

[18] K. Thonke, Th. Gruber, N. Teoﬁlov, R. Sch

€

onfelder, A. Waag and R. Sauer, Physica B

308–310 945 (2001).

[19] D.C. Reynolds, D.C. Look, B. Jogai, C.W. Litton, T.C. Colins, W. Harsch and G. Cantwell,

Phys. Rev. B 57, 19 (1998).

[20] K. Nassau, C.H. Henryand J.W. Shiever,in Proceedings of the Tenth International Conference

of the Physics of Semiconductors, NBS, Springﬁeld, 1970, p. 629.

[21] B.K. Meyer, J. Sann, S. Lautenschlaeger, M.R. Wagner and A. Hoffmann, Phys. Rev. B

76, 184120 (2007).

[22] J.L. Merz, H. Kukimoto, K. Nassau and J.W. Shiever, Phys. Rev. B 6, 545 (1972).

[23] B. S

antic, C. Merz; U. Kaufmann, R. Niebuhr, H. Obloh and K. Bachem, Appl. Phys. Lett.

71, 1837 (1997).

[24] D.M. Hofmann, A. Hofstaetter, F. Leiter, H. Zhou, F. Henecker and B.K. Meyer, Phys. Rev.

Lett. 88, 045504 (2002).

[25] M. Schilling, R. Helbig and G. Pensl, J. Lumin. 33, 201 (1985).

[26] C. Gonzales, D. Block, R.T. Cox and A. Herv



e, J. Crystal Growth 59, 357 (1982).

[27] H.J. Ko, Y.F. Chen. S.K. Hong, H. Wenisch and T. Yao, Appl. Phys. Lett. 77, 3761 (2000).

[28] F. Reuss, C. Kirchner, Th. Gruber, R. Kling, S. Maschek, W. Limmer, A. Waag and

P. Ziemann, J. Appl. Phys. 95, 3385 (2004).

[29] S. M

€

uller, D. Stichtenoth, M. Uhrmacher, H. Hofs

€

ass, C. Ronning and J. R

€

oder, Appl. Phys.

Lett. 90, 012107 (2007).

[30] J.R. Haynes, Phys. Rev. Lett. 4, 361 (1960).

[31] A.V. Rodina, M. Strassburg, M. Dworzak, U. Haboeck, A. Hoffmann, A. Zeuner, H.R. Alves,

D.M. Hofmann and B.K. Meyer, Phys. Rev. B 69, 125206 (2004).

[32] D.G. Thomas, J. Phys. Chem. Solids 3, 229 (1957).

[33] K.I. Hagemark, J. Solid State Chem. 16, 293 (1976).

[34] A.F. Kohan, G. Ceder, D. Morgan and C.G. Van de Walle, Phys. Rev. B 61, 15019 (2000).

[35] D.C. Oh, T. Suzuki, J.J. Kim, H. Makino, T. Hanada, M.W. Ch,and T. Yao, Appl. Phys. Lett.

86, 032909 (2005).

[36] N. Shohata, T. Matsumura and T. Ohno, Jpn. J. Appl. Phys. 19, 1793 (1980).

[37] A. Rohatgi, S.K. Pang, T.K. Gupta and W.D. Straub, J. Appl. Phys. 63, 5375 (1988).

[38] W.I. Lee, R.L. Young and W.K. Chen, J. Appl. Phys., Part 2 35, L1158 (1996).

[39] N. Ohashi, J. Tanaka, T. Ohgaki, H. Haneda, N. Ozawa and T. Tsurumi, J. Mater. Res.

17, 1529 (2002).

[40] F.D. Auret, S.A. Goodman, M. Legodi, W.E. Meyer and D.C. Look, Appl. Phys. Lett. 80, 1340

(2002).

[41] D.C. Look, J. W. Hemsky and J. R. Sizelove, Phys. Rev. Lett. 82, 2552 (1999).

[42] B.K. Meyer, S. Lautenschlaeger, S. Graubner, C. Neumann and J. Sann, Mater. Res. Soc.

Symp. 891, 0891-EE08-02.1 (2006).

[43] Hang-Ju Ko, Takafumi Yao, Yefan Chen and Soon-Ku Hong, J. Appl. Phys. 92, 8 (2002).

References 167

[44] A.P. Roth and D.F. Williams, J. Appl. Phys. 52 , 6685 (1982).

[45] E. Ziegler, A. Heinrich, H. Oppermann and G. Stoever, Phys. Status Solidi A 66, 635 (1981).

[46] Y. Natsume, H. Sakata and T. Hirayama, Phys. Status Solidi A 148, 484 (1995).

[47] Y. Natsume, H. Sakata, T. Hirayama and H. Yanagida, J. Appl. Phys. 72, 4203 (1992).

[48] K.I. Hagemark and L.C. Chacka, J. Solid State Chem. 15, 261 (1975).

[49] K. Minegishi, Y. Koiwai, Y. Kikuchi, K. Yano, M. Kasuga and A. Shimizu, Jpn. J. Appl. Phys.

36, L1453 (1997).

[50] M. Joseph, H. Tabata and T. Kawai, Jpn. J. Appl. Phys. 38, L1205 (1999).

[51] D.C. Look, D.C. Reynolds, C.W. Litton, R.L. Jones, D.B. Eason and G. Gantwell, Appl. Phys.

Lett. 81, 1830 (2002).

[52] Y.R. Ryu, S. Zhu, D.C. Look, J.M. Wrobel, H.M. Jeong and H.W. White, J. Crystal Growth

216, 330 (2000).

[53] Y.R. Ryu, W.J. Kim and H.W. White, J. Crystal Growth 219, 419 (2000).

[54] Y.R. Ryu, T.S. Lee and H.W. White, Appl. Phys. Lett. 83, 87 (2003).

[55] A. Tsukazaki, A. Ohtomo, T. Onuma, M. Oktami, T. Makino, M. Sumiya, K. Oktami, S.F.

Chichibu, S. Fuke, Y. Segawa, H. Ohno, H. Koinuma and M. Kawasaki, Nat. Mater. 4,42

(2005).

[56] K.-K. Kim, H.-S. Kim, D.-K. Hwang, J.-H. Lim and S.-J. Park, Appl. Phys. Lett. 83,63

(2003).

[57] O.F. Schirmer, J. Phys. Chem. Solids 29, 1407 (1968).

[58] D. Zwingel and F. G

€

artner, Solid State Commun. 14, 45 (1974).

[59] R.T. Cox, D. Block, A. Herv



e, R. Picard and C. Santier, Solid State Commun. 25, 77 (1978).

[60] J. Qiu, J.M. De Puydt, H. Cheng and M.A. Haase, Appl. Phys. Lett. 59, 2992 (1991).

[61] L. Svob, C. Thiandoume, A. Lusson, M. Bouanani, Y. Marfaing and O. Gorochov, Appl. Phys.

Lett. 76, 1696 (2000).

[62] C.H. Park, S.B. Zhang,and S.-H. Wei, Phys. Rev. B 66, 073202 (2002).

[63] S.B. Zhang, S.-H. Wie and A. Zunger, Phys. Rev. B 63, 075205 (2001).

[64] E.-C. Lee, K. Y.-G. Jin and K.J. Chang, Phys. Rev. B 64, 085120 (2001).

[65] G. Xiong, K.B. Ucer, R.T. Williams, J. Lee, D. Bhattacharyya, J. Metson and P. Evans, J. Appl.

Phys. 97, 043528 (2005).

[66] A. Zeuner, H. Alves, D.M. Hofmann, B.K. Meyer, A. Hoffmann, U. Haboeck, M. Strassburg

and M. Dworzak, Phys. Status Solidi B 234, R7 (2002).

[67] J.F. Rommelu



ere, L. Svob, F. Jomard, J. Mimila-Arroyo, A. Lusson. V. Sallet and Y. Marfaing,

Appl. Phys. Lett. 83, 287 (2003).

[68] S. Yamauchi, Y. Goto and T. Hariu, J. Cryst. Growth 260, 1 (2004).

[69] T. Tamura, T. Makino, A. Tsukazaki, M. Sumiya, S. Fuke, T. Furumochi, M. Lippmaa, C.H.

Chia, Y. Segawa, H. Koinuma and M. Kawasaki, Solid State Commun. 127, 265 (2003).

[70] B.K. Meyer, J. Sann, D.M. Hofmann, C. Neumann and A. Zeuner, Semicond. Sci. Technol.

20, S62 (2005).

[71] A. Kaschner, U. Haboeck, Martin Strassburg, Matthias Strassburg, G. Kaczmarczyk, A.

Hoffmann, C. Thomsen, A. Zeuner, H.R. Alves, D.M. Hofmann and B.K. Meyer, Appl. Phys.

Lett. 80, 1909 (2002).

[72] Lijun Wang and N.C. Giles, Appl. Phys. Lett. 84, 16 (2004).

[73] T. C. Damen, S. P. S. Porto and B. Tell, Phys. Rev. 142, 570 (1966).

[74] J. M. Calleja and M. Cardona, Phys. Rev. B 16, 3753 (1977).

[75] X. Wang, S. Yang, J. Wang, M. Li, X. Jiang, G. Du, X. Liu and R. P. H. Chang, J. Cryst.

Growth 226, 123 (2001).

[76] L. Sugiura, M. Suzuki and J. Nishio, Appl. Phys. Lett. 72, 1748 (1998).

[77] E.-C. Lee, Y.-S. Kim, Y.-G. Jin and K. J. Chang, Phys. Rev. B 64, 085120 (2001).

[78] A. Kaschner, H. Siegle, G. Kaczmarczyk, M. Straßburg, A. Hoffmann, C. Thomsen, U. Birkle,

S. Einfeldt and D. Hommel, Appl. Phys. Lett. 74, 3281 (1999).

[79] S. Lautenschl

€

ager,unpublished, Giessen (2007).

[80] M. Schirra, R. Schneider, A. Reiser, G.M. Prinz, M. Feneberg, J. Biskupek, U. Kaiser, C.E.

Krill, K. Thonke and R. Sauer, Phys. Rev. B 77, 125215 (2008).

[81] T.S. Jeong, M.S. Han, C.J. Youn and Y.S. Park, J. Appl. Phys. 96, 175 (2004).

168 Spectral Identiﬁcation of Impurities and Native Defects in ZnO

[82] D.-K. Hwang, H.-S. Kim, J.-H. Lim, J.-Y. Oh, J.-H. Yang, S.-J. Park, K.-K. Kim, D.C. Look

and Y.S. Park, Appl. Phys. Lett. 86, 151917 (2005).

[83] J.D. Ye, S.L. Gu, F. Li, M. Zhu, R. Zhang, Y. Shi, Y.D. Zheng, X.W. Sun, G.Q. Lo and

D.L. Kwang, Appl. Phys. Lett. 90, 152108 (2007).

[84] F.X. Xiu, Z. Yang, L.J. Mandalapu, D.T. Zhao and J.L. Liu, Appl. Phys. Lett. 87, 252102

(2005).

[85] N. Volbers, S. Lautenschl

€

ager, T. Leichtweiss, A. Laufer, S. Graubner, B.K. Meyer, K. Potzger

and S. Zhou, J. Appl. Phys. 103, 123106 (2008).

[86] A. Abragam and B. Bleany, Electron Paramagnetic Resonance of Transition Ions, Oxford

University Press, Oxford, 1970.

[87] J. Schneider and A. R

€

auber, Z. Naturforsch. 16a, 712 (1961).

[88] P.H. Kasai, Phys. Rev. 130, 989 (1963).

[89] M. Schulz, Phys. Status Solidi A 27, K5 (1975).

[90] D. Block, A. Herv



e and R.T. Cox, Phys. Rev. B 25, 6049 (1982).

[91] N.Y. Garces, N.C. Giles, L.E. Halliburton, G. Cantwell, D.B. Eason, D.C. Reynolds and

D.C. Look, Appl. Phys. Lett. 80, 1334 (2002).

[92] S. Orlinskii, J. Schmidt, P. G. Baranov, V. Lormann, I. Riedel, D. Rauh and V. Dyakonov,

Phys. Rev. B 77, 115334 (2008).

[93] C. G. Van de Walle and J. Neugebauer, Nature 423, 626 (2003).

[94] S. F. Cox, E. A. Davis, S. P. Cottrell, P. J. King, J. S. Lord, J. M. Gil, H. V. Alberto, R. C. Vil

ao,

J. Piroto Duarte, N. Ayres de Campos, A. Weidinger, R. L. Lichti,and S. J. Irvine, Phys. Rev.

Lett. 86, 2601 (2001).

[95] Yu. V.Gorelkinskii and G.D. Watkins, Phys. Rev. B 69, 115212 (2004).

[96] L.S. Vlasenko and G.D. Watkins, Phys. Rev B 71, 125210 (2005).

[97] L.S. Vlasenko and G.D. Watkins, Phys. Rev B 72, 035203 (2005).

[98] N.T. Son, I.G. Ivanov, A. Kuznetsov, B.G. Svensson, Q.X. Zhao, M. Willander, N. Morishita,

T. Oshima, H. Itoh, J. Isoya, E. Janz



en and R. Yakimova, J. Appl. Phys. 102, 093504 (2007).

[99] J.M. Smith and W.E. Vehse, Phys. Lett.A 31, 147 (1970).

[100] V. Soriano and D. Galland, Phys. Status Solidi B 77, 739 (1976).

[101] C. Gonzales, D. Galland and A. Herve, Phys. Status Solidi B 72, 309 (1975).

[102] B. Schallenberger and A. Hausmann, Z. Phys. B 23

, 177 (1976).

[103] B. Schallenberger and A. Hausmann, Z. Phys. B: Condens. Matter 44, 143 (1981).

[104] R. Laio, L.S. Vlasenko and P.M. Vlasenko, J. Appl. Phys. 103, 12379 (2008).

[105] S.B. Zhang, S.-H. Wei and A. Zunger, Phys. Rev. B 63, 075205 (2001).

[106] F.H. Leiter, H.R. Alves, A. Hofstaetter, D.M. Hofmann and B.K. Meyer, Phys. Status Solidi B

226, R4 (2001).

[107] A. Janotti and C.G. Van de Walle, Phys. Rev. B 76, 165202 (2007).

[108] W.E. Carlos, E.R. Glaser and D.C. Look, Physica B 308–310 976 (2001).

[109] L.S. Vlasenko and G.D. Watkins, Phys. Rev. B 71, 125210 (2005).

[110] P. Edel, F.J. Ahlers, C.M. Mc Donagh, B. Henderson and J.M. Spaeth, J. Phys. C 15, 4913

(1982).

[111] P. Edel, C. Hennies, Y. Merle d’Aubign



e, R. Romestain and Y. Twarowski, Phys. Rev. Lett. 28,

19 (1972).

[112] B. Henderson and G.F. Imbusch,in Optical Spectroscopy of Inorganic Solid, Clarendon Press,

Oxford, 1989, p. 563.

[113] J.J. Davies, G.N. Aliev, S.J. Bingham, D. Wolverson, S. Stepanov, B. Yavich and W.N. Wang,

Phys. Rev. B 67, 035203 (2003).

[114] J. Schneider and O. Schirmer, Z. Naturforsch. 18a, 20 (1963).

[115] O.F. Schirmer, J. Phys. Chem. Solids 29, 1407 (1968).

[116] D. Zwingel and F. G

€

artner, Solid State Commun. 14, 45 (1974).

[117] O.F. Schirmer, H.A. M

€

uller and J. Schneider, Phys. Kondens. Mater. 3, 323 (1965).

[118] J.R. Morton and K.F. Preston, J. Magn. Reson. 30, 577 (1978).

[119] B.K. Meyer, A. Hofstaetter and V.V. Laguta, Physica B 376, 682 (2006).

[120] F.H. Leiter,PhD thesis, Gießen, 2002.

References 169

[121] J. Sann, A. Hofstaetter, D. Pﬁsterer, J. Stehr and B.K. Meyer, Phys. Status Solidi C 3, 952

(2006).

[122] J.J. Lander, J. Phys. Chem. Solids 15, 324 (1960).

[123] D. Zwingel, J. Lumin. 5, 385 (1972).

[124] L.E. Halliburton, Lijun Wang, Lihua Bai, N.Y. Garces, N.C. Giles, M.J. Callahan and Buguo

Wang, J. Appl. Phys. 96, 7168 (2004).

[125] S.B. Orlinskii, J. Schmidt, P.G. Baranov, D.M. Hofmann, C.M. Donega and A. Meijerink,

Phys. Rev. Lett. 92, 047603–1 (2004).

[126] D. Pﬁsterer, J. Sann, D.M. Hofmann, M. Plana, A. Neumann, M. Lerch and B.K. Meyer, Phys.

Status Solidi B 243, R1 (2006).

[127] N.Y. Garces, Lijun Wang, N.C. Giles, L.E. Halliburton, G. Cantwell and D.B. Eason, J. Appl.

Phys. 94, 519 (2003).

[128] S. Larach and J. Turkevich, J. Phys. Chem. Solids 29, 1519.

[129] G.N. Aliev, S.J. Bingham, D. Wolverson, J.J. Davis, H. Makino, H.J. Ko and T. Yao, Phys.

Rev. B 70, 115206 (2004).

[130] J. Sann, J. Stehr, A. Hofstaetter, D.M. Hofmann, A. Neumann, M. Lerch, U. Haboeck, A.

Hoffmann and C. Thomsen, Phys. Rev. B 76, 195203 (2007).

[131] K. Leutwein and J. Schneider, Z. Naturforsch. 26a, 1236 (1971).

[132] A.L. Taylor, G. Filipovich and G.K. Lindeberg, Solid State Commun. 8, 1359 (1970).

[133] D. Galland and A. Herve, Solid State Commun. 14, 953 (1974).

[134] P.B. Dorain, Phys. Rev. 112, 1058 (1958).

[135] W.W. Walsh and L.W. Rupp, Phys. Rev. 126, 952 (1962).

[136] A. Hausmann, Phys. Status Solidi 31, K131 (1969).

[137] W.C. Holton, J. Schneider and T.L. Estle, Phys. Rev. 133, A1638 (1964).

[138] R.E. Dietz, H. Kamimura, M.D. Sturge and A. Yariv, Phys. Rev. 132, 1559 (1963).

[139] A. Hausmann and E. Blaschke, Z. Phys. 230, 255 (1970).

[140] J. Stehr, C. Knies, A. Hofstaetter, D.M. Hofmann, W. Xu, Y. Zhou and X. Zhang, Solid State

Commun. 145, 95 (2008).

[141] G. Born, A. Hofstaetter and A. Scharmann, Z. Phys. 240, 163 (1970).

170 Spectral Identiﬁcation of Impurities and Native Defects in ZnO

Vapor Transport Growth of ZnO

Substrates and Homoepitaxy of ZnO

Device Layers

Gene Cantwell

, Jizhi Zhang

and J.J. Song

1,2

ZN Technology, Inc., Brea, CA, USA

Department of Electrical and Computer Engineering, University of California at

San Diego, La Jolla, CA, USA

7.1 Introduction

Vapor growth methods have been used to produce high quality single crystals of compound

semiconductors in the II–VI family for many years.

[1–4]

This is primarily due to the high

vapor pressures of the components of these compounds well below their melting points

along with their typically high melting points. The vapor growth methods are usually

either physical vapor transport (PVT) or chemical vapor transport (CVT). PVT, in this

case, refers to the sublimation of the compound into components volatile at the growth

temperatures and has often been favored for the more volatile II–VI compounds such as

CdS, CdTe, ZnTe, CdSe, and ZnSe. The less volatile II–VI compounds, primarily ZnS and

ZnO, often require a transporting agent to react with the compound and accomplish the

vaporization of the compound’s components at practical growth temperatures; thus

chemical vapor transport or CVT. The potential transporting agents that have been used

with ZnO form an extensive list including hydrogen, carbon, and group VII compounds.

[5]

Zinc Oxide Materials for Electronic and Optoelectronic Device Applications, First Edition.

Edited by Cole W. Litton, Donald C. Reynolds and Thomas C. Collins.