Tunable SiGe Detectors.
Final technical rept. Oct 95-Oct 96,
CALSPAN UB RESEARCH CENTER BUFFALO NY
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The theory of voltage tunable cut off wavelength silicideSiGeSi detectors is presented. Experimental data on tunable PtSiSiGeSi detectors is also presented. The theory is able to account for the experimentally observed behavior of tunable PtSiSiGeSi diodes. The tunability provided by the SiGe layer is understood as being due to two related effects first, keeping the barrier peak position fixed with bias and second, moving the barrier peak further away from the interface. The second effect decreases quantum efficiency, which depends on the peak to interface distance. However, maximizing the first effect allows us to obtain desired levels of tunability without potential decreases in quantum efficiency. For voltage switched, dual window imaging, a tunable range of 5-12 microns is required over moderate voltages 10-15 volts, for which calculated detector parameters are Ge percentages of at least 20, and total SiGe thicknesses uniform plus graded of approx. 60-100 A and boron doping levels of approx. 4-8 x 10 to the 16th cm-3 throughout the depletion layer width approx. 4000 A, in the SiGe and in the underlying S1.
- Infrared Detection and Detectors