The electrical characterization of a tunable wavelength surface light-emitting device is reported. The device consists of p-GaAs and n-Ga1—xAlxAs heterojunction containing an inversion layer on the p-side, and GaAs quantum wells on the n-side, and is referred to as HELLISH-2 (Hot Electron Light Emitting and Lasing in Semiconductor Heterojunction). We studied two HELLISH-2 devices by using standard Hall, SdH (Shubnikov de Haas) and high-speed I–V measurement techniques. 2D carrier density and transport mobility were obtained from standard Hall measurements and quantum lifetime and quantum mobility were determined from SdH measurements. A detailed analysis of the results has been performed to understand the scattering processes involved in device operation. We have concluded that a good knowledge of electrical parameters is important in order to optimize the device structures based on our model calculations.