TY - JOUR
T1 - Heteroepitaxial CdTe(111) grown by MBE on nominally flat and misoriented Si(001) substrates
T2 - Characterization by electron microscopy and optical methods
AU - Tsen, S. C Y
AU - Smith, David
AU - Hutchins, J. W.
AU - Skromme, Brian
AU - Chen, Y. P.
AU - Sivananthan, S.
N1 - Funding Information:
This work was supported by AFOSR (ARPA) Contract F49620-94-C-0080. The electron microscopy was conducted at the Center for High Resolution Electron Microscopy at Arizona State University supported by the National Science Foundation under Grant No. DMR-9314326.
PY - 1996/2
Y1 - 1996/2
N2 - Transmission electron microscopy (TEM), and low temperature reflectance and photoluminescence (PL) have been used to characterize heteroepitaxial CdTe(111) layers grown by molecular beam epitaxy directly onto nominally flat and misoriented Si(001) substrates. TEM observations confirmed that 1° offcut toward [110] in the Si(001) substrate suppressed formation of double domains, while increasing the azimuthal angle of the offcut relative to [110] suppressed twin formation. Under optimized growth conditions, residual twinning defects disappeared within about 2 μm from the substrate. Atomic-scale details of interfaces in this system were successfully recorded. Clear splitting of exciton states at the direct gap in optical reflectance and PL spectra demonstrated the existence of residual biaxial tensile strain of about 7 × 10-4 in the CdTe layers, due to thermal expansion mismatch. A strain-shifted neutral acceptor-bound exciton peak dominated the 1.7 K photoluminescence spectrum, together with donor-to-acceptor and band-to-acceptor transitions involving a 49 meV shallow acceptor level. The sharpness of bound exciton peaks (about 0.6 meV full width at half maximum) supported the high layer quality.
AB - Transmission electron microscopy (TEM), and low temperature reflectance and photoluminescence (PL) have been used to characterize heteroepitaxial CdTe(111) layers grown by molecular beam epitaxy directly onto nominally flat and misoriented Si(001) substrates. TEM observations confirmed that 1° offcut toward [110] in the Si(001) substrate suppressed formation of double domains, while increasing the azimuthal angle of the offcut relative to [110] suppressed twin formation. Under optimized growth conditions, residual twinning defects disappeared within about 2 μm from the substrate. Atomic-scale details of interfaces in this system were successfully recorded. Clear splitting of exciton states at the direct gap in optical reflectance and PL spectra demonstrated the existence of residual biaxial tensile strain of about 7 × 10-4 in the CdTe layers, due to thermal expansion mismatch. A strain-shifted neutral acceptor-bound exciton peak dominated the 1.7 K photoluminescence spectrum, together with donor-to-acceptor and band-to-acceptor transitions involving a 49 meV shallow acceptor level. The sharpness of bound exciton peaks (about 0.6 meV full width at half maximum) supported the high layer quality.
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U2 - 10.1016/0022-0248(95)00823-3
DO - 10.1016/0022-0248(95)00823-3
M3 - Article
AN - SCOPUS:0030562216
SN - 0022-0248
VL - 159
SP - 58
EP - 63
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
IS - 1-4
ER -