Alloy Fluctuation Effect on Electronic Transition Properties of DX Center Observed with Modified Deep Level Transient Spectroscopy

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Abstract
Alloy fluctuation effects in electronic transition properties of the DX center have been studied in a selectively Si doped Al0.3Ga0.7As/GaAs heterostructure grown by molecular beam epitaxy. Using deep-level-transient-spectroscopy (DLTS) technique, we have measured the drain current transient, from an applied sale pulse for a long gate high-electron-mobility-transistor biased in a linear region. This scheme enables us to record DLTS-like spectra not only for the electron emission process but also for the electron capture process of the DX center. From the analysis of these spectra, we found capture and emission activation energies with Gaussian distributions having wide and narrow band-widths, respectively. This can be explained by considering the large fluctuations of electronic states and the small fluctuations of the spring constant and Jahn-Teller splitting parameter in the DX center cell.