Influence of Dual-Frequency Plasma-Enhanced Chemical-Vapor Deposition Si3N4 Passivation on the Electrical Characteristics of AlGaN/GaN Heterostructure Field-Effect Transistors
Authors: Tan, W.S.; Houston, P.A.; Hill, G.; Airey, R.J.; Parbook, P.J.
Source: Journal of Electronic Materials, Volume 33, Number 5, 1 May 2004 , pp. 400-407(8)
Abstract:The influence of dielectric stress on the direct current (DC) electrical characteristics of AlGaN/GaN heterostructure field-effect transistors (HFETs) has been investigated. Dual-frequency plasma deposition was used to vary the amount of stress induced by a passivating dielectric on the surface of the devices. Initial data suggested a strong influence from the induced dielectric stress, but the low-frequency, radio-frequency (RF) excitation of the plasma deposition process was found to induce a severe nonreversible damage to the exposed AlGaN surface through N ion bombardment. The consequence is a drastic reduction of the sheet carrier concentration and mobility of the two-dimensional electron gas (2DEG). Subsequently, an alternative damage-free technique using a helium precursor was used to obtain compressive films. Based on the results, uniform dielectric stress has a minimal impact on the polarization charges within the AlGaN barrier.
Document Type: Research article
Publication date: 2004-05-01