为了研究In Al N材料的光学参数随温度的变化特性,采用变温椭圆偏振光谱(25～600℃)测量技术对In Al N合金材料在193～1 650 nm宽光谱范围内进行了表征。利用Tauc-Lorentz振子模型描述和拟合变温椭偏光谱测量数据,得到了In Al N薄膜的...为了研究In Al N材料的光学参数随温度的变化特性,采用变温椭圆偏振光谱(25～600℃)测量技术对In Al N合金材料在193～1 650 nm宽光谱范围内进行了表征。利用Tauc-Lorentz振子模型描述和拟合变温椭偏光谱测量数据,得到了In Al N薄膜的光学常数(n、k和α)随温度的变化曲线。由变化曲线可见,在温度50～600℃,光学带隙从4. 56 e V减小到4. 35 e V,折射率峰值对应的能量则从4. 61 e V减小到4. 37 e V。两者都随温度升高而减小,其变化规律符合Varshni方程的预期。结果表明,在600℃以下测试温度条件下,In Al N合金材料的光谱和光学参数没有发生突变,说明In Al N合金材料具有高的热稳定性,并未发生影响材料光学性能的晶体结构变化。展开更多
A high performance InAlN/GaN high electron mobility transistor(HEMT)at low voltage operation(6-10 V drain voltage)has been fabricated.An 8 nm InAlN barrier layer is adopted to generate large 2DEG density thus to reduc...A high performance InAlN/GaN high electron mobility transistor(HEMT)at low voltage operation(6-10 V drain voltage)has been fabricated.An 8 nm InAlN barrier layer is adopted to generate large 2DEG density thus to reduce sheet resistance.Highly scaled lateral dimension(1.2μm source-drain spacing)is to reduce access resistance.Both low sheet resistance of the InAlN/GaN structure and scaled lateral dimension contribute to an high extrinsic transconductance of 550 mS/mm and a large drain current of 2.3 A/mm with low on-resistance(Ron)of 0.9Ω·mm.Small signal measurement shows an fT/fmax of 131 GHz/196 GHz.Large signal measurement shows that the InAlN/GaN HEMT can yield 64.7%-52.7%(Vds=6-10 V)power added efficiency(PAE)associated with 1.6-2.4 W/mm output power density at 8 GHz.These results demonstrate that GaN-based HEMTs not only have advantages in the existing high voltage power and high frequency rf field,but also are attractive for low voltage mobile compatible rf applications.展开更多
In this work, we use a 3-nm-thick Al0.64In0.36N back-barrier layer in In0.17Al0.83N/GaN high-electron mobility transistor （HEMT） to enhance electron confinement. Based on two-dimensional device simulations, the infl...In this work, we use a 3-nm-thick Al0.64In0.36N back-barrier layer in In0.17Al0.83N/GaN high-electron mobility transistor （HEMT） to enhance electron confinement. Based on two-dimensional device simulations, the influences of Al0.64In0.36N back-barrier on the direct-current （DC） and radio-frequency （RF） characteristics of InAlN/GaN HEMT are investigated, theoretically. It is shown that an effective conduction band discontinuity of approximately 0.5 eV is created by the 3-nm-thick Al0.64In0.36N back-barrier and no parasitic electron channel is formed. Comparing with the conventional InAlN/GaN HEMT, the electron confinement of the back-barrier HEMT is significantly improved, which allows a good immunity to short-channel effect （SCE） for gate length decreasing down to 60 nm （9-nm top barrier）. For a 70-nm gate length, the peak current gain cut-off frequency （fT） and power gain cut-off frequency （fmax） of the back-barrier HEMT are 172 GHz and 217 GHz, respectively, which are higher than those of the conventional HEMT with the same gate length.展开更多
In order to investigate the influence of compressive strain on indium incorporation in In Al N and In Ga N ternary nitrides, In Al N/Ga N heterostructures and In Ga N films were grown by metal–organic chemical vapor ...In order to investigate the influence of compressive strain on indium incorporation in In Al N and In Ga N ternary nitrides, In Al N/Ga N heterostructures and In Ga N films were grown by metal–organic chemical vapor deposition. For the heterostructures, different compressive strains are produced by Ga N buffer layers grown on unpatterned and patterned sapphire substrates thanks to the distinct growth mode; while for the In Ga N films, compressive strains are changed by employing Al Ga N templates with different aluminum compositions. By various characterization methods, we find that the compressive strain will hamper the indium incorporation in both In Al N and In Ga N. Furthermore, compressive strain is conducive to suppress the non-uniform distribution of indium in In Ga N ternary alloys.展开更多
文摘为了研究In Al N材料的光学参数随温度的变化特性,采用变温椭圆偏振光谱(25～600℃)测量技术对In Al N合金材料在193～1 650 nm宽光谱范围内进行了表征。利用Tauc-Lorentz振子模型描述和拟合变温椭偏光谱测量数据,得到了In Al N薄膜的光学常数(n、k和α)随温度的变化曲线。由变化曲线可见,在温度50～600℃,光学带隙从4. 56 e V减小到4. 35 e V,折射率峰值对应的能量则从4. 61 e V减小到4. 37 e V。两者都随温度升高而减小,其变化规律符合Varshni方程的预期。结果表明,在600℃以下测试温度条件下,In Al N合金材料的光谱和光学参数没有发生突变,说明In Al N合金材料具有高的热稳定性,并未发生影响材料光学性能的晶体结构变化。
基金Project supported by the China Postdoctoral Science Foundation(Grant No.2018M640957)the Fundamental Research Funds for the Central Universities,China(Grant No.20101196761)+2 种基金the National Natural Science Foundation of China(Grant No.61904135)the National Defense Pre-Research Foundation of China(Grant No.31513020307)the Natural Science Foundation of Shaanxi Province of China(Grant No.2020JQ-316).
文摘A high performance InAlN/GaN high electron mobility transistor(HEMT)at low voltage operation(6-10 V drain voltage)has been fabricated.An 8 nm InAlN barrier layer is adopted to generate large 2DEG density thus to reduce sheet resistance.Highly scaled lateral dimension(1.2μm source-drain spacing)is to reduce access resistance.Both low sheet resistance of the InAlN/GaN structure and scaled lateral dimension contribute to an high extrinsic transconductance of 550 mS/mm and a large drain current of 2.3 A/mm with low on-resistance(Ron)of 0.9Ω·mm.Small signal measurement shows an fT/fmax of 131 GHz/196 GHz.Large signal measurement shows that the InAlN/GaN HEMT can yield 64.7%-52.7%(Vds=6-10 V)power added efficiency(PAE)associated with 1.6-2.4 W/mm output power density at 8 GHz.These results demonstrate that GaN-based HEMTs not only have advantages in the existing high voltage power and high frequency rf field,but also are attractive for low voltage mobile compatible rf applications.
基金supported by the Natural Science Foundation of Hebei Province,China(Grant No.F2013202256)
文摘In this work, we use a 3-nm-thick Al0.64In0.36N back-barrier layer in In0.17Al0.83N/GaN high-electron mobility transistor （HEMT） to enhance electron confinement. Based on two-dimensional device simulations, the influences of Al0.64In0.36N back-barrier on the direct-current （DC） and radio-frequency （RF） characteristics of InAlN/GaN HEMT are investigated, theoretically. It is shown that an effective conduction band discontinuity of approximately 0.5 eV is created by the 3-nm-thick Al0.64In0.36N back-barrier and no parasitic electron channel is formed. Comparing with the conventional InAlN/GaN HEMT, the electron confinement of the back-barrier HEMT is significantly improved, which allows a good immunity to short-channel effect （SCE） for gate length decreasing down to 60 nm （9-nm top barrier）. For a 70-nm gate length, the peak current gain cut-off frequency （fT） and power gain cut-off frequency （fmax） of the back-barrier HEMT are 172 GHz and 217 GHz, respectively, which are higher than those of the conventional HEMT with the same gate length.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61404099 and 61306017)the Fundamental Research Funds for the Central Universities,China(Grant No.JB141101)
文摘In order to investigate the influence of compressive strain on indium incorporation in In Al N and In Ga N ternary nitrides, In Al N/Ga N heterostructures and In Ga N films were grown by metal–organic chemical vapor deposition. For the heterostructures, different compressive strains are produced by Ga N buffer layers grown on unpatterned and patterned sapphire substrates thanks to the distinct growth mode; while for the In Ga N films, compressive strains are changed by employing Al Ga N templates with different aluminum compositions. By various characterization methods, we find that the compressive strain will hamper the indium incorporation in both In Al N and In Ga N. Furthermore, compressive strain is conducive to suppress the non-uniform distribution of indium in In Ga N ternary alloys.
