Metalorganic Vapor-Phase Epitaxy In-Situ Growth of P-On-N and N-On-P Hg1-Xcdxte Junction Photodiodes Using Tertiarybutylarsine As the Acceptor Source

We report arsenic doping of Hg1-xCdxTe (0.2 < x < 0.3) grown using metalorganic vapor phase epitaxy (MOVPE) by the direct alloy growth (DAG) technique. Tertiarybutylarsine (TBAs) was used as a precursor for As doping. Several epilayers were grown at different Hg partial pressures and TBAs bubbler temperatures in order to study the doping characteristics. The amount of As incorporated in the layer as well as the acceptor concentration were found to be a strong function of the Hg pressure. Secondary ion mass spectrometric studies on heterostructures showed that the compositional interdiffusion is less than the diffusion of As during growth. P-N junctions were grown using TBAs for the first time and several of these layers were processed to fabricate photodiodes. A p-on-n grown junction photodiode with a cutoff wavelength of 8.2 μm had an RoA value of 241 ohm-cm2 at 80K and is the highest reported value for p-on-n DAG-MOVPE devices. Methods to improve the device RoA of the grown junctions are also proposed.