Determination of the Nonlinear Photocurrent Response of AlGaN via 2-Beam Action Spectroscopy

Despite the increasingly growing demand for materials able to undergo multiphoton absorption, the accurate characterization of the nonlinear responses of such materials remains challenging. We employ 2-beam constant-amplitude photocurrent (2-BCAmP) spectroscopy to study nonlinear photocurrent generation in the wide band gap semiconductor AlGaN. Through the use of 2-BCAmP, the nonlinear photocurrent response of the AlGaN photodiodes was studied at a wavelength range of 740-840nm using a mode locked, Ti:sapphire excitation source. The 2-BCAmP experiments reveal the presence of two different orders of absorption in the photodiode. 2-BCAmP experiments at different photocurrents further show that the contributing mechanism is a combination of 2-photon absorption and linear absorption.