Numerical Analysis of the Effect of P-Regions on the I-V Kink in GaAs MESFETs

Kazuya NISHIHORI  Yasuyuki MIYAMOTO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E90-C   No.8   pp.1643-1649
Publication Date: 2007/08/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.8.1643
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Semiconductor Materials and Devices
Keyword: 
GaAs MESFET,  buried-p-type,  p-pocket-type,  I-V kink,  impact ionization,  hole accumulation,  

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Summary: 
In this paper, we describe the effect of p-regions on the I-V kink in GaAs FETs. A kink-free p-pocket-type self-aligned gate GaAs MESFET (PP-MESFET), which does not include p-regions under the channel, has been analyzed and compared with a conventional buried-p-type self-aligned gate GaAs MESFET (BP-MESFET) using two-dimensional device simulation. The relation between the I-V kink and the layout of p-regions has been demonstrated by numerical simulation for the first time. For both the BP-MESFET and PP-MESFET, impact ionization produces holes in high-field regions. The holes accumulate under the channel, widen the channel, and cause an abrupt increase in drain current in turn in the BP-MESFET. On the other hand, in the PP-MESFET, holes generated in the high-field region are transported to the source region easily over the lower barrier owing to the absence of p-regions under the channel. Holes do not accumulate under the channel, leading to kink-free I-V characteristics of the PP-MESFET. P-regions should be located so as not to cause the accumulation of holes in GaAs FETs where p-regions are required for high-frequency performance.