Journal of the Institute of Electronics Engineers of Korea SD (대한전자공학회논문지SD)

The Institute of Electronics and Information Engineers (대한전자공학회)
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An Analytical Model for the I-V Characteristics of a Short Channel AlGaN/GaN HEMT with Piezoelectric and Spontaneous Polarizations

압전 및 자발 분극을 고려한 단채널 AlGaN/GaN HEMT의 전류-전압 특성에 관한 해석적 모델

  • Oh Young-Hae (School of Electronic & Electrical Engineering, Hongik University) ;
  • Ji Soon-Koo (School of Electronic & Electrical Engineering, Hongik University) ;
  • Suh Chung-Ha (School of Electronic & Electrical Engineering, Hongik University)
  • 오영해 (홍익대학교 전자전기공학부) ;
  • 지순구 (홍익대학교 전자전기공학부) ;
  • 서정하 (홍익대학교 전자전기공학부)
  • Published : 2005.12.01
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Abstract

In this paper, in order to derive the current-voltage characteristics of n-AlGaN/GaN HEMTs with the piezoelectric and spontaneous polarizations, we suggested analytical solutions for the two-dimensional Poisson equation in the AlGaN and GaN regions by taking into account the longitudinal field variation, field-dependent mobility, and the continuity condition of the channel current flowing in the quantum well. Obtained expressions for long and short channel devices would be applicable to the entire operating regions in a unified manner. Simulation results show that the drain saturation current increases and the cutoff voltage decreases as drain voltage increases. Compared with the conventional models, the present model seems to provide more reasonable explanation for the drain-induced threshold voltage roll-off and the channel length modulation effect.

본 논문에서는 압전 및 자발 분극 효과를 내포한 단채널 n-AlGaN/GaN HEMT의 전류-전압 특성을 도출하고자 AlGaN 및 GaN층 내에서 분극을 고려한 2차원 Poisson 방정식의 해법을 제안하였다. AlGaN 및 GaN층에서의 2차원적 전위 변화를 채널전류의 연속조건과 컨시스턴트하게 도출하기 위해서 GaN영역에 형성된 양자 우물을 통해 흐르는 전자에 대한 전계-의존 이동도를 고려하였다. 도출된 표현식은 동작 전압 전 영역과 장/단채널 소자에 대하여 일괄적으로 적용될 수 있을 것으로 보이며, 계산 결과로부터 2차원 전위 분포 변화 효과를 고려하기 위한 파라미터 ${\alpha}$의 도입이 타당함을 보이고 있다. 이로써, 본 모델은 기존의 모델에 비해 드레인 전압의 증가에 따른 드레인 포화전류의 증가 및 문턱 전압의 감소 현상 등을 보다 적절히 설명할 수 있음을 보이고 있다.

Keywords

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