SBIR-STTR Award

Techniques for the reduction of growth-induced crystal defects are of critical importance to the efforts geared toward development of thin-film heteroepitaxial materials and devices for infrared sensor applications based on large-area semiconductor substrates. These defects, such as threading and misfit dislocations, commonly occurring during growth and processing of the respective heteroepitaxial material systems, can adversely impact the performance and reliability of the fabricated infrared focal plane array (IRFPA) devices, particularly those for long-wave infrared (LWIR) detection. This impact will be most severe if these defects are situated in the infrared device active region and so can interfere with its electrical functionality. Aimed toward reduction and mitigation of the above crystal defects, this Phase I proposal presents a systematic approach for their characterization and analysis using electron beam-induced current (EBIC) in a scanning transmission electron microscope (STEM). In this proposal, special emphasis is placed on the expected key challenges of meeting optimal specimen preparation requirements as well as overcoming the intrinsic and inherent charge collection issue, such as dark current noise, specific to the respective material systems.

Electron beam-induced current in scanning transmission electron microscopy technique will be required in order to gain insight and actionable information for development of crystal defect reduction and mitigation strategies for the new generation of high-performance solid-state infrared focal plane arrays. Although the proof-of-concept for the application of technique to semiconductor photonic devices was partially demonstrated in a series of legacy academic and industrial research efforts in the 1970s and 1980s, the challenges associated with its specimen preparation requirements had yet to be overcome. The Phase I of this program did successfully overcome these challenges and also developed and demonstrated a key alternate charge collection characterization technique. In the Phase II of this program, the newly-developed specimen preparation methodology will be improved further and utilized for the analysis of advanced single-junction and multi-junction infrared photonic devices of interest to, and/or directly provided by the Army.