Effect of Ge Composition on Infrared Detecting Performance of Strain Si/${\rm Si}_{1-{\rm x}-{\rm y}}{\rm Ge}_{\rm x} {\rm C} _{\rm y}$ Heterojunction on Preferentially Etched Silicon Substrate

The p-strain Si/i-${\rm Si}_{1-{\rm x}-{\rm y}}{\rm Ge}_{\rm x} {\rm C} _{\rm y}$ heterojunctions prepared by a rapid thermal chemical vapor deposition system on an n-Si substrate with back preferentially etched were developed for fast IR detecting applications. The stress induced by the p-strain Si/i-${\rm Si}_{1-{\rm x}-{\rm y}}{\rm Ge}_{\rm x} {\rm C} _{\rm y}$ heterojunction enhanced the carrier mobility in p-Si layer, while the preferentially etching of n-Si substrate accelerated the heat dissipating and the reduction of series resistance. As a result, the device achieved a better performance than that of the conventional one without the strain Si or the preferentially etched substrate. In addition, the effects of morphology and Ge composition in the i-${\rm Si}_{1-{\rm x}-{\rm y}}{\rm Ge}_{\rm x} {\rm C} _{\rm y}$ thin film on the IR detecting performance were investigated in details.