Characteristics of MOCVD-grown high-quality CdTe layers on GaAs substrates

CdTe epitaxial layers are grown successfully on a (100)-GaAs substrate by metallorganic chemical vapor deposition (MOCVD) using dimethylcadmium (DMCd) and diethyltelluride (DETe) as alkyl sources. The CdTe epilayers grown between 365 °C and 380 °C possess the best surface morphology. DETe is used as the controlling species of this growth system. Typical growth rates are varied from 2.5 μm/hr to 5.3 μm/hr. Low-temperature (12K) photoluminescence (PL) measurements reveal that 380 °C is the best growth temperature and the full width at half maximum (FWHM) of the dominated peak is about 1.583 eV by the bound-exciton emission of 9.38 meV. The double crystal X-ray rocking curves (DCRC) indicate that the FWHM decreases while increasing the epilayer thickness and approaches a stable value about 80 arc sec under the growth rate of 5.2 μm/hr, the growth temperature of 380 °C and the DETe/DMCd concentration ratio of 1.7. The value of 80 arc sec in FWHM is the smallest one ever reported to date.