Investigation of deep energy levels in heterostructures based on GaN by DLTS

Abstract

In this paper we report our results of DLTS investigations of deep-level defects in Schottky-gate AlGaN/GaN LP-MOVPE structures grown on sapphire substrate. The exact location of heterostructure's interface below the surface (20 nm) was determined from the concentration profile to depletion region width dependence. The free charge carrier density was calculated (n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2D</sub> = 4.75÷5.09 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ). Four deep energy levels have been identified from selected DLTFS spectra (activation energies: E1=E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> -0.545 eV, E2=E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> -0.599 eV, E3=E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> -0.642 eV, and E4=EC-1,118 eV).