Silicon-Based Infrared Imaging Sensor

A Phase I effort to investigate the use of poly-crystalline Ge-on-Si and strained SiGe alloy grown on silicon for near-infrared photodetectors is proposed. These devices are expected to cover the spectral band that stretches from a wavelength of 0.8 to 1.6 microns. If reasonable performance devices can be fabricated, this will potentially pave the way for the integration of signal processing electronics with the detectors using standard CMOS process technology. The culmination of the effort (in Phase II) would then be the demonstration of near-infrared focal-plane imaging and sensing arrays. These low-cost arrays could potentially be used in certain applications in lieu of systems made from exotic compound semiconductor materials such as HgCdTe, InSb, or InGaAs. Specifically, in applications where short-distance sensing or imaging is important. The proposed work will investigate heterojunction diodes fabricated from poly-Ge grown (by thermal evaporation) on Si as well as strained heterojunction single-crystalline SiGe diodes grown on Si obtained from commercially available sources. Basic device characteristics, including (i) photocurrent, (ii) dark current, (iii) noise current, (iv) conversion efficiency, and (v) detectivity will be studied. A correlation of these characteristics with theoretical models will be conducted to aid in the optimization of the device structures.