A NEW N-TYPE DOPING PRECURSOR FOR MOCVD-IMP GROWTH OF DETECTOR QUALITY MCT

A new indium precursor, triisopropyl indium (TIPIn), has been used for doping MCT at low carrier concentrations. Previous attempts using indium organometallics resulted in a strong memory effect where residual doping would persist for many growth runs. Introducing TIPIn on the tellurium inject line resulted in a similarly strong memory doping but this was not observed when feeding the dopant in on the cadmium injection line. The TIPIn is believed to have been forming a low volatility adduct with diisopropyl tellurium (DIPTe) in the feed line and to have continued to evaporate at a low but significant rate. By keeping the TIPIn and DIPTe precursors separate until they entered the reactor, the desired low 10(15) cm-3 carrier concentration and flat indium profiles could be achieved with good reproducibility. Good electrical characteristics were measured for these layers with Auger limited lifetime >1 mus at 77K.