Electric-field-induced second-harmonic generation in GaN devices

Electric-field-induced second-harmonic generation is used to detect electri c fields in a GaN UV Schottky photodiode and in a GaN light-emitting diode. The second-harmonic signal is measured as a function of bias voltage and i ncident laser power. This technique is sensitive to small applied voltages and can be used to track electronic waveforms. The photocurrent generated b y this technique is found to be less than 100 pA when the fundamental and s econd-harmonic frequencies are both below the device bandgap. (C) 2001 Opti cal Society of America.