Resonant-cavity MSM photodetector employing a Burstein-shifted In/sub 0.49/Ga/sub 0.51/P-GaAs reflector

The InGaAsP-GaAs material system is an alternative to AlGaAs-GaAs for optoelectronics, but has the disadvantage of relatively low refractive index differences. This makes implementation of vertical-cavity Bragg reflector devices a greater challenge. The maximum index difference is obtained for In/sub 0.49/Ga/sub 0.51/P-GaAs; mirrors based on this combination are inefficient in the 800-880-nm wavelength region due to absorption in the GaAs layers. The mirror efficiency can be improved by exploiting band-filling (Burstein-Moss) effects in heavily doped GaAs. This possibility was demonstrated by fabrication of resonant-cavity metal-semiconductor-metal photodetectors operating near 800-nm wavelength. A responsivity of 0.34 A/W was obtained with a 410-nm-thick absorption layer.