HgCdTe photovoltaic detectors fabricated using a new junction formation technology

Abstract

The current–voltage characteristics measured over a wide temperature range are reported for HgCdTe mid-wavelength infrared n-on-p photodiodes fabricated using a novel junction formation technology. The planar homojunction device junctions were formed on LPE grown vacancy doped HgCdTe using a reactive ion etching (RIE) plasma induced conversion process. The zero bias dynamic resistance–junction area product, R o A, was 4.6×10 7 Ω cm 2 at 80 K and is comparable to the best planar diodes reported using conventional ion implantation junction formation technology. Arrhenius plots of R o A exhibit an activation energy equal to the bandgap, E g, and show that the diodes are diffusion limited for temperatures ≥135 K. A series of temperature dependent 1/ f noise measurements were performed, indicating that the activation energy for 1/ f noise in the region where the diodes are diffusion limited is 0.7 E g. Energies close to this value have previously been associated with Hg vacancies in HgCdTe. These results are similar to those obtained from high quality HgCdTe photodiodes fabricated using mature ion implantation technology. However, the plasma based technology used in this work is significantly less complex and does not require any high temperature annealing steps.