Capacitance Spectroscopy of Heteroepitaxial AlGaAs/GaAs p–i–n Structures.

The temperature dependences of the capacitance-voltage (C–V) characteristics and deep-level spectra of a graded high-voltage AlxGa1 –xAs p0–i–n0 junction grown by liquid-phase epitaxy via autodoping with background impurities are studied. Changes in the C–V characteristics at varied measurement temperature and optical illumination demonstrate that the p0-, i-, and n0-type layers in AlxGa1 –xAs under study contain bistable DX centers. Spectra furnished by deep-level transient spectroscopy (DLTS), measured at various bias voltages Vr and filling-pulse voltages Vf, show a positive DLTS peak for the n0-type layer, with a thermal activation energy of Et = 280 meV and electron-capture cross section of σn = 3.17 × 10–14 cm2, which is unusual for a majority-charge-carrier trap. This peak is attributed to the negatively charged state of the Se/Te donor impurity, which is a bistable DX center with negative correlation energy U. [ABSTRACT FROM AUTHOR]