Improvement of Hg0.78Cd0.22Te diode characteristics by hydrogenation

Hg0.78Cd0.22Te n on p photovoltaic diodes were fabricated with the wafers grown by liquid-phase epitaxy on CdTe substrate which have a cutoff wavelength of 10.5 mu m The wafer was doped with Hg vacancies and the acceptor concentration was 5 x 10(15) - 2 x 10(16) /cm(3). We applied the planar ion-implantation technique for the junction formation. Post-implantation annealing was performed to improve reverse bias characteristics and RoA value. Using this method, we obtained RoA values of 2 - 8 Omega cm(2) at 77K. However, the increase of RoA by post-implantation annealing saturated as the annealing time increased further. This limit is thought to come from the low minority carrier lifetime in the Hg vacancy doped wafer. To improve the device performance further, we adapted the hydrogenation technique. The RoA of the hydrogenated diode was found to be 70 similar to 120 Omega cm(2), which is one order of magnitude higher than that of the post-implantation annealed diode. From the model fitting analysis, the hydrogenation effect was attributed to the increase of the minority carrier lifetime.