Integrated Technology in MCT/GaAs and MCT/Si for Medium and Long Wavelength Infrared

MCT layers have been grown by MOCVD on CdTe, GaAs and GaAsSi for device processing. Both 111 and 100MCT have been grown on GaAs and the relative merits of the two orientations are discussed. The effects of the substrate preparation, pre-bake, nucleation and buffer growth conditions led to 100MCT layers being p-type as grown with FWHMs of 80-90 arc seconds. CdTe has been grown on 311A and B GaAs. The CdTe adopts one of several orientations 100 OR 3-4 DEG 311 and is untwinned with a relatively smooth surface morphology. Continuing studies of CdTe growth on Si indicate that the nucleation temperature should be higher than 450 C. Annealing studies have been carried out to establish material of a consistent p-type carrier concentration for processing, and to understand the diffusion mechanism within the material. A reproducible p-type anneal has been established. Linear arrays of LWIR and MWIR diodes have been formed in MCTGaAs by diffusion through a ZnS mask. 77K R sub o A products obtained over a range of cut-off wavelengths are comparable to the state-of-the-art literature values. R sub o As of 10 ohm-cm-sq have been obtained for arrays with a 11 micron cut-off. Keywords Infrared detectors, Photovoltaic devices.