STUDY OF MSM PHOTODETECTOR FABRICATED ON POROUS SILICON

A p-type porous silicon MSM (metal-semiconductor-metal) photodetector has been fabricated and its performance investigated. Samples with different anodization times are compared and the optimum photoresponse is obtained from a sample etched for 3 min at an anodization current of 25 mA/cm2. The spectral response of the MSM photodetector is found to be similar to that of a Si PIN photodiode. A deep electron trap with activation energy E(a) = 0.44-0.53 eV, capture cross section sigma = 2.6 x 10(-16)-1.3 x 10(-15) cm2 and trap concentration N(t) = 5.4 x 10(14)-3.5 x 10(13) cm-3 is observed from the metal-oxide-porous silicon structure. The degradation of the photoluminescence intensity and the photocurrent response is presented. A thin silicon oxide film coating on the MSM photodetector is shown to improve the device stability.