Effects of buffer layer thickness and doping concentration on SiC MESFET characteristics
Effects of buffer layer thickness and doping concentration on SiC MESFET characteristics
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DOI：
10.1142/s0129156404003009
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发表时间：
2004-08
期刊：
影响因子：
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通讯作者：
SANKHA S. Mukherjee;SYED S. Islam
中科院分区：
文献类型：
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作者：
SANKHA S. Mukherjee;SYED S. Islam
使用Atlas/spl reg/ device simulator进行了二维模拟，研究了缓冲层厚度和掺杂浓度对SiC MESFET电特性的影响。研究了缓冲层厚度和掺杂浓度对器件的介电常数、输出电阻、栅源电容、栅漏电容和截止频率f/sub T/的影响。结果表明，通过增加缓冲层的掺杂浓度和/或增加缓冲层的厚度，可以降低高漏偏压下沟道载流子向衬底的泄漏，从而提高MESFET的性能。对于具有0.3/spl mu/m的缓冲层厚度和1/spl mu/m的栅极长度的SiC MESFET，随着缓冲层掺杂密度从1.9/spl乘以/10/sup 17/ cm/sup-3/降低到1/spl乘以/10/sup 16/ cm/sup-3/，漏电流从0.1A//spl mu/m增加到0.45A//spl mu/m以上。模拟是在栅源电压为-1V和漏源电压为15 V的情况下进行的。在相同条件下，输出电阻从1.2/spl × 10/sup 6/ /spl Ω///spl μ/m减小到1.0/spl × 10/sup 5/ /spl Ω///spl μ/m，输出阻抗从5.9mS//spl μ/m减小到5.3mS//spl μ/m，输出频率从11 GHz减小到8 GHz。
Two-dimensional simulations have been carried out using the Atlas/spl reg/ device simulator to investigate the effects of the buffer layer thickness and doping concentration on the electrical characteristics of the SiC MESFET. The variations of transconductance, output resistance, gate-source capacitance, gate-drain capacitance and (cutoff frequency) f/sub T/ with respect to the change in buffer layer thickness and doping concentration have been investigated. It is observed that the performances of MESFET can be improved by reducing the leakage of channel carrier into the substrate at high drain bias, which is achieved by increasing buffer layer doping density and/or increasing buffer layer thickness. For a SiC MESFET with buffer layer thickness of 0.3/spl mu/m and gate length of 1/spl mu/m, drain current increases from 0.1 A//spl mu/m to above 0.45A//spl mu/m as the buffer layer doping density is decreased from 1.9/spl times/10/sup 17/ cm/sup -3/ to 1/spl times/10/sup 16/ cm/sup -3/. The simulations were carried out at a gate-source voltage of -1V and a drain-source voltage of 15V. Under similar conditions, the output resistance decreases from 1.2/spl times/10/sup 6/ /spl Omega///spl mu/m to 1.0/spl times/10/sup 5/ /spl Omega///spl mu/m, and the transconductance decreases from 5.9mS//spl mu/m to 5.3mS//spl mu/m, and f/sub T/ decreases from 11GHz to 8GHz.