NONEXPONENTIALITY IN PHOTOINDUCED CURRENT TRANSIENTS IN UNDOPED SEMIINSULATING GALLIUM-ARSENIDE

An isothermal spectroscopic technique called time-analyzed transient spectroscopy (TATS) has been used to study photoinduced current transients in undoped semi-insulating GaAs. It is demonstrated that this has many advantages over conventionally used photoinduced transient spectroscopy (PITS). Specifically, TATS provides both quantitative measure and qualitative insights to the nonexponentiality of current transients commonly encountered in these materials. Using this spectroscopy, features related to enigmatic negative peaks resulting from rising current transients in these materials are reported. A simple kinetic model has been proposed to explain the essential features of rising transients leading to negative peaks in both TATS and PITS spectra. © 1995 American Institute of Physics.