Parasitic effects and traps in AlGaN/GaN HEMT on sapphire substrate

¹ Laboratoire de Micro-Optoélectroniques et Nanostructures, Faculté des Sciences de Monastir, Avenue de l'Environnement, 5000 Monastir, Tunisia
² Institut d'Électronique de Microélectronique et de Nanotechnologie IEMN (TIGER), Département hyperfréquences et Semiconducteurs, Université des Sciences et Technologies de Lille, Avenue Poincaré, 59652 Villeneuve d'Ascq Cedex, France

Corresponding author: gassoumimalek@yahoo.fr

Received: 17 March 2010
Revised: 3 May 2010
Accepted: 17 May 2010
Published online: 24 June 2010

Abstract

AlGaN/GaN high electron mobility transistors (HEMTs) with sapphire (Al₂O₃) substrates reveal anomalies like kink effect, current collapse, hysteresis phenomena on I_ds-V_ds and I_ds-V_gs. These parasitic effects can be attributed to the presence of traps in the hetero-structure. Deep defects analysis was performed by conductance deep level transient spectroscopy (CDLTS) under drain pulse. Four electron traps have been detected with activation energy and capture cross-section of 2.62 eV, 1.18 eV, 0.97 eV, 0.48 eV, σ_n = 2.4 × 10^-17 cm² and σ_n = 2.37 × 10^-14 cm², σ_n = 2 × 10^-12 cm² and σ_n = 4.67 × 10^-14 cm² respectively. The localisation and the identification of these traps have occurred and a correlation between defects and parasitic effects has been discussed.