Evaluatio n of the Built-i n Voltage of a Au/ n-GaAs Schottky Barrier Diode by Usi ng Electroreflecta nce Spectroscopy

The built-in voltage (V bi ) of a Au/n-GaAs Schottky barrier diode was examined by using electroreflectance (ER) spectroscopy. The ER spectra were measured at various modulation voltages (v ac ) and dc bias voltages (V bias ). The interface electric fields (E i ) were obtained from the observed Franz-Keldysh oscillations (FKO) in the ER spectra. When v ac was increased, the amplitudes of the ER spectra varied linearly, but the line shapes of the ER spectra did not change. E i decreased from 19.3 × 104 V/cm to 4.39 × 104 V/cm with increasing V bias from −0.5 V to 0.6 V. From the relationship between V bias and E i 2 , the V bi and the carrier concentration (n) were found to be 0.70 V and 2.4 × 1016 cm −3, respectively.