Passivation of Dislocation Defects by Hydrogenation for High Performance Longwave Infrared (LWIR) HgCdTe on Silicon

For reasons primarily related to a lack of a suitable lattice matched substrate and the need to integrate with Si ROIC's, there is a need for delivery of low defect density HgCdTe epilayers on Si. Despite the significant lattice mismatch between Si and HgCdTe several US companies have demonstrated that it is possible to obtain high performance MBE grown MWIR (3-5 microns)-HgCdTe devices on large area Si substrates. This MWIR success cannot, however, be directly translated to LWIR (8-12 microns)-HgCdTe detectors because of their increased sensitivity to material etch pit density. Due to this, it is necessary to develop techniques for reducing and/or electrically neutralizing the defects originating at the substrate/epilayer interface. It is well established that hydrogenation can be used to passivate defects in III-V and group IV semiconductor materials. Very little work has been reported on the effects, electrical or otherwise, of hydrogenation of II-VI materials. In this Phase I we propose to study the effects of hydrogenation on the electrical activity of defects in MBE grown HgCdTe epilayers on Si(211)B substrates. The results obtained in Phase I will be used to optimize a process technology to enable fabrication of high performance MBE grown LWIR HgCdTe on Si. In Phase II a prototype focal plane array will be fabricated using the passivation process developed and the performance demonstrated by acquiring 77K imagery.