TY - JOUR
T1 - Surface morphology and defect formation mechanisms for HgCdTe (211)B grown by molecular beam epitaxy
AU - Chang, Yong
AU - Becker, C. R.
AU - Grein, C. H.
AU - Zhao, J.
AU - Fulk, C.
AU - Casselman, T.
AU - Kiran, R.
AU - Wang, X. J.
AU - Robinson, E.
AU - An, S. Y.
AU - Mallick, S.
AU - Sivananthan, S.
AU - Aoki, T.
AU - Wang, C. Z.
AU - Smith, David
AU - Velicu, S.
AU - Zhao, J.
AU - Crocco, J.
AU - Chen, Y.
AU - Brill, G.
AU - Wijewarnasuriya, P. S.
AU - Dhar, N.
AU - Sporken, R.
AU - Nathan, V.
N1 - Funding Information:
The authors thank Dr. Choi from US Army Research Laboratory for SEM and EDS measurements. This work was partially supported by the DoD Multidisciplinary University Research Initiative (MURI) program administered by the Army Research Office and monitored by Dr. W. W. Clark under Grant No. DAAD19-01-1-406 and also partially supported by ARO SBIR program under Contract Numbers W911NF-05-C-0090/W911NF-07-C-0001 subcontracted through EPIR Technologies, Inc. We acknowledge the use of facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University as well as the scanning probe microscope system purchased under support of Defense University Research Instrument Program (DURIP) administrated by the Army Research Office.
PY - 2008/9
Y1 - 2008/9
N2 - The surface morphology and crystallinity of HgCdTe films grown by molecular beam epitaxy (MBE) on both CdZnTe and CdTe/Si (211)B substrates were characterized using atomic force microscopy (AFM), as well as scanning (SEM) and transmission (TEM) electron microscopy. Crosshatch patterns and sandy-beach-like morphologies were commonly found on MBE (211) HgCdTe epilayers grown on both CdZnTe and CdTe/Si substrates. The patterns were oriented along the [2̄13], [2̄31], and [01̄1] directions, which were associated with the intersection between the (211) growth plane and each of the eight equivalent HgCdTe slip planes. This was caused by strain-driven operation of slip in these systems with relative large Schmid factor, and was accompanied by dislocation formation as well as surface strain relief. Surface crater defects were associated with relatively high growth temperature and/or low Hg flux, whereas microtwins were associated with relatively low growth temperature and/or high Hg flux. AFM and electron microscopy were used to reveal the formation mechanisms of these defects. HgCdTe/HgCdTe superlattices with layer composition differences of less than 2% were grown by MBE on CdZnTe substrates in order to clarify the formation mechanisms of void defects. The micrographs directly revealed the spiral nature of growth, hence demonstrating that the formation of void defects could be associated with the Burton, Cabrera, and Frank (BCF) growth mode. Void defects, including microvoids and craters, were caused by screw defect clusters, which could be triggered by Te precipitates, impurities, dust, other contamination or flakes. Needle defects originated from screw defect clusters linearly aligned along the [01̄1] directions with opposite Burgers vector directions. They were visible in HgCdTe epilayers grown on interfacial superlattices. Hillocks were generated owing to twin growth of void or needle defects on (111) planes due to low growth temperature and the corresponding insufficient Hg movement on the growth surface. Therefore, in addition to nucleation and growth of HgCdTe in the normal two-dimensional layer growth mode, the BCF growth mode played an important role and should be taken into account during investigation of HgCdTe MBE growth mechanisms.
AB - The surface morphology and crystallinity of HgCdTe films grown by molecular beam epitaxy (MBE) on both CdZnTe and CdTe/Si (211)B substrates were characterized using atomic force microscopy (AFM), as well as scanning (SEM) and transmission (TEM) electron microscopy. Crosshatch patterns and sandy-beach-like morphologies were commonly found on MBE (211) HgCdTe epilayers grown on both CdZnTe and CdTe/Si substrates. The patterns were oriented along the [2̄13], [2̄31], and [01̄1] directions, which were associated with the intersection between the (211) growth plane and each of the eight equivalent HgCdTe slip planes. This was caused by strain-driven operation of slip in these systems with relative large Schmid factor, and was accompanied by dislocation formation as well as surface strain relief. Surface crater defects were associated with relatively high growth temperature and/or low Hg flux, whereas microtwins were associated with relatively low growth temperature and/or high Hg flux. AFM and electron microscopy were used to reveal the formation mechanisms of these defects. HgCdTe/HgCdTe superlattices with layer composition differences of less than 2% were grown by MBE on CdZnTe substrates in order to clarify the formation mechanisms of void defects. The micrographs directly revealed the spiral nature of growth, hence demonstrating that the formation of void defects could be associated with the Burton, Cabrera, and Frank (BCF) growth mode. Void defects, including microvoids and craters, were caused by screw defect clusters, which could be triggered by Te precipitates, impurities, dust, other contamination or flakes. Needle defects originated from screw defect clusters linearly aligned along the [01̄1] directions with opposite Burgers vector directions. They were visible in HgCdTe epilayers grown on interfacial superlattices. Hillocks were generated owing to twin growth of void or needle defects on (111) planes due to low growth temperature and the corresponding insufficient Hg movement on the growth surface. Therefore, in addition to nucleation and growth of HgCdTe in the normal two-dimensional layer growth mode, the BCF growth mode played an important role and should be taken into account during investigation of HgCdTe MBE growth mechanisms.
KW - Burgers vector
KW - Defect
KW - Dislocation
KW - HgCdTe
KW - Molecular beam epitaxy
KW - Schmid factor
KW - Slip
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U2 - 10.1007/s11664-008-0477-5
DO - 10.1007/s11664-008-0477-5
M3 - Article
AN - SCOPUS:51849132041
SN - 0361-5235
VL - 37
SP - 1171
EP - 1183
JO - Journal of Electronic Materials
JF - Journal of Electronic Materials
IS - 9
ER -