An Implant-Passivated Blocked Impurity Band Germanium Detector for the Far Infrared

We propose to investigate the feasibility of fabricating a germanium blocked-impurity-band (BIB) detector using a novel process which will enable us to: 1- fabricate a suitably-doped active layer using the well-established bulk crystal-growth process, which guarantees excellent dopant control and extremely low compensating impurities, and 2- grow the blocking layer using an implant-passivation technique which will produce the required high purity and a very sharp transition from the active to blocking layer. These features are key in design and optimization of multi-layered structure of BIBs, and their implementation and quality are crucial in optimum operation of these detectors. The proposed process is a drastic departure from conventional epitaxial methods, such as chemical vapor deposition and liquid phase epitaxy, which have yet to produce far IR BIBs suitable for astronomical instruments. Germanium BIBs will offer extended wavelength response to at least 200µm, high quantum efficiency, high immunity to ionizing radiation, and elimination of long-term transient and memory effects. Coupled with their compatibility with Si cryo-CMOS readout multiplexers and the planar, bump-bond hybridization process, these detectors will make possible the construction of large format, high sensitivity FPAs for far IR astronomy and will replace the current unstressed and stressed germanium detectors.