Mechanism and properties of point-contact metal-insulator-metal diode detectors at 10.6 μ

Abstract

Detection mechanisms of point-contact MIM diodes at 10.6 μ wavelength have been studied. Detailed measurements of the static current-voltage characteristic and its first and second derivatives as functions of bias voltage were made simultaneously with infrared sensitivity measurements. The results indicate that the static current-voltage characteristics extend to infrared frequencies. We find that thermal effects do not contribute significantly to detection at this wavelength, and that the tungsten whisker acts as a rather efficient receiving antenna. The antenna and its shunting capacitance apply a 3×1013-Hz ac voltage to the diode which in our experiment has amplitude 124 mV, through an impedance which is much less than the junction impedance. The diode nonlinearity d2I/dV2 varies from 6.5×10−5 to 6.7×10−3 A/V2 as dc bias increases from 0 to 300 mV. None of these conclusions apply to detection at 6328 Å; it is found that detection in the visible is dominated by thermal or photoconductive effects.