High intensity submillimeter photoresponse of a Si inversion layer

Abstract

The submillimeter wave (496, 385, and 66 μm) photoresponse has been measured in an n-channel Si metal-oxide-semiconductor field-effect transistor at 4.2 K. A fast (≤10 ns) response is observed only in the low carrier density (ns) regime where the dc conductance is activated. Nonlinear photo response is found for I≥10 kW/cm2 and the signal follows a simple saturation behavior. The peak illuminated effective mobility is ∼13 000 cm2/Vs (at ns∼0.7×1011 cm−2) which is more than a factor of 2 larger than the peak 4.2-K mobility of the device (at ns∼2.4×1012 cm−2). At carrier densities greater than 5×1011 cm−2 the response is bolometric with a response time ∼1 μs.