  We report here the first observation of a pyroelectric effect in a non-polar
semiconductor. This effect originates in the temperature dependent electric
dipole of the p-n junction. The junction was illuminated by a chopped CO2 laser
beam, and periodic and single-pulse pyroelectric signals were observed and
measured as a function of temperature, reverse bias voltage and chopper
frequency. The measured pyroelectric coefficient is about 10^(-3) microC/cm2K
in the region of 40-80 K. The theoretical model describes quantitatively all
experimental features. The time evolution of the temperature inside the
junction region was reconstructed.
