Theoretical study of a GaN-AlGaN high electron mobility transistor including a nonlinear polarization model

• Published in: IEEE transactions on electron devices Vol. 50; no. 2; pp. 315 - 323
• Main Authors: Tsung-Hsing Yu, Brennan, K.F.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2003; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Alloys; Aluminum compounds; Charge carrier density; Electron mobility; Gallium compounds; High electron mobility transistors; Mathematical analysis; Mathematical models; MODFETs; Nonlinearity; Polarization; Semiconductor device modeling; Semiconductor devices
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2002.808519

We present a theoretical model of an AlGaN-GaN high electron mobility field effect transistor (HEMT) that includes a nonlinear model of the strain polarization fields produced at the heterointerface. Recent experimental work has indicated that the macroscopic polarization in III-nitride alloys is a nonlinear function of the material composition. It is well known that the behavior of a GaN-AlGaN HEMT depends greatly upon the properties of the strain-induced polarization fields formed at the GaN-AlGaN heterointerface. It is the purpose of this paper to provide a detailed model of a GaN-AlGaN HEMT that includes a nonlinear formulation of the polarization. The model is found to agree well with recent experimental measurements made for GaN-AlGaN HEMTs when the nonlinear polarization model is included. The cutoff frequency, transconductance, and current-voltage characteristics are computed. The effect of the nonlinear polarization model on the sheet carrier density is also presented.