Modelling of capacitance and threshold voltage for ultrathin normally-off AlGaN/GaN MOSHEMT

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• 作者：R SWAIN ; K JENA ; T R LENKA
• 关键词：Two ; dimensional electron gas ; density of state ; high electron mobility transistor ; metal oxide semiconductor high electron mobility transistor ; normally ; off ; quantum capacitance.
• 刊名：Pramana
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：88
• 期：1
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Physics, general; Astronomy, Observations and Techniques; Astrophysics and Astroparticles;
• 出版者：Springer India
• ISSN：0973-7111
• 卷排序：88

文摘

A compact quantitative model based on oxide semiconductor interface density of states (DOS) is proposed for Al_0.25Ga_0.75N/GaN metal oxide semiconductor high electron mobility transistor (MOSHEMT). Mathematical expressions for surface potential, sheet charge concentration, gate capacitance and threshold voltage have been derived. The gate capacitance behaviour is studied in terms of capacitance–voltage (CV) characteristics. Similarly, the predicted threshold voltage (V_T) is analysed by varying barrier thickness and oxide thickness. The positive V_T obtained for a very thin 3 nm AlGaN barrier layer enables the enhancement mode operation of the MOSHEMT. These devices, along with depletion mode devices, are basic constituents of cascode configuration in power electronic circuits. The expressions developed are used in conventional long-channel HEMT drain current equation and evaluated to obtain different DC characteristics. The obtained results are compared with experimental data taken from literature which show good agreement and hence endorse the proposed model.