Mid-wave infrared HgCdTe photodiode technology based on plasma induced p-to-n type conversion

[Truncated abstract] Infrared photodiodes fabricated in HgCdTe achieve near-ideal performance, however, in comparison with other semiconductors, processing techniques for HgCdTe are expensive and have relatively low yields. Reactive-ion-etching (RIE) in a H2⁄CH4 gas mixture, a process primarily used for material removal, will cause p-to-n type conversion in HgCdTe. It has been shown, by several groups, that infrared photodiodes fabricated with a process technology based on RIE p-to-n type-conversion achieve high yields with state-of-the-art performance. For this technology to be accepted RIE formed n-on-p photodiodes must demonstrate junction stability under normal operating conditions. Along with a stable junction, a compatible passivation technology that is able to withstand processing and operation temperatures is required. This thesis investigates the RIE p-to-n type-conversion mechanism in HgCdTe with the aim of demonstrating bake stable RIE formed junctions, and gaining an insight to the processes by which RIE type-conversion occurs. In pursuing these aims, two complimentary objectives were required, namely, the development of a passivation technology compatible with RIE formed junctions, and the development of a detailed I-V/Rd-V model for HgCdTe photodiodes. As a result of these objectives, this thesis presents a double-layer ZnS on CdTe passivation technology with which stable RIE-formed n-on-p junctions in HgCdTe are demonstrated. Using this process technology, mid-wave infrared (MWIR) HgCdTe photodiodes have been fabricated and subjected to a bake in vacuum at 80°C for 175 hours, after which there is negligible degradation in the zero-bias Dynamic-Resistance Area product (RoA) from the pre-bake values