Space charge and oscillation effects in gold-doped silicon p-‘i’-n diodes☆

Abstract Properties of Au-doped Si p-‘i’-n diodes in the region of the I–V characteristics preceding the usual double injection negative resistance have been examined. At lowest applied voltages the I–V characteristic obeys Ohm's law. With the voltage increased to the point where the time required for electrons to cross the ‘i’ region becomes comparable to the electron lifetime, the I–V characteristic in many cases deviates from Ohm's law to a cubic dependence of the current on the applied voltage. This region is described by a modification of a known theory of electron-hole space-charge-limited emission. As the applied voltage is increased further, a point is reached in the I–V characteristic where the current both deviates from a cubic dependence on applied voltage and develops an oscillatory component which can vary in frequency from about 5 to greater than 100 MHz. These oscillations occur in a positive resistance region of the I–V characteristic.