Novel Si homojunction far-infrared detectors

A novel concept to develop far-infrared (FIR) Si detectors is proposed based on homojunction internal photoemission. As the first approach, a 48 mum lambda (c) Si FIR detector is demonstrated on molecular beam epitaxy (MBE) grown homojunction multilayers consisting of highly doped emitter layers and undoped intrinsic layers. The detector shows high responsivity over a wide wavelength range with a peak responsivity of 12.3 +/- 0.1 A/W at 27.5 mum and detectivity D* of 6.6x10(10) cmHz(1/2)/W at 4.2K. The lambda (c) and bias dependent quantum efficiency agree well with theory. Based on the experimental results and the model, Si FIR detectors (40 similar to 200 mum) with high performance and tailorable lambda (c) can be realized using higher emitter layer doping concentrations.