Rapid Thermal Diffusion of Indium in p-HgCdTe/CdTe

In this study, the rapid thermal diffusion (RTD) of indium and its activation as a donor in p-Hg0.70Cd0.30Te/CdTe were investigated using atomic indium and electron concentration profiles obtained by secondary ion mass spectroscopy (SIMS) and differential Hall measurements, respectively. Photodiodes with a junction formed by the RTD of indium were also demonstrated. There are two diffusion components, a complementary error function fitted atomic diffusion component and an exponentially fitted fast diffusion component. The diffusion coefficients of atomic indium into p-Hg0.70Cd0.30Te by RTD can be fitted as D(T)( cm2/s)=1.45×10-2exp (-0.772(eV)/kT) in the temperature range of 100–200°C. It is observed that diffused indium atoms are partially activated as donors and that the ratio of electron to diffused indium concentration is increased with increased diffusion depth from the surface. For photodiodes with an indium RTD junction, trap-assisted tunneling current is markedly suppressed. The origin of suppression of trap-assisted tunneling current can be explained by suppression of defect generation in the depletion region during junction formation by the RTD process.