Measurement of the Surface Electrical Potential in a Planar Avalanche Photodiode Near Breakdown.
01 January 1990
The surface voltage profile of an avalanche photodiode has been measured by monitoring the energy shift of the indium MNN Auger transition in a scanning Auger microprobe. The electric field on the surface of the diode at the p-n junction when the diode is biased just below breakdown was found to be 3 x 10 sup 5 V/cm. A small voltage drop across the p sup - guard ring was also observed and then confirmed with electron beam induced current. This voltage drop indicated that the diode depletion layer extended across the guard ring. The excellent spatial resolution (0.2microns) and voltage precision (+-2 volts) achieved in this study demonstrate the value of this method for measuring high junction electric fields in many planar devices.