异质结场效应晶体管太赫兹探测器非线性响应

Nonlinear response of terahertz detectors based on heterostructure field effect transistors

基于描述AlGaN/GaN材料异质结中二维电子气(2DEG)浓度与漂移速度的流体动力学方程组,采用有限差分法对一维空间的非线性耦合偏微分方程组进行合适的时间和空间离散,计算场效应晶体管探测器在不同强度和不同频率入射太赫兹信号作用下的暂态响应波形及输出直流电压(漏源极之间的开路电压),并定量分析了在恒定栅源电压作用下探测器的实际输出(非线性响应)与现有的小信号线性理论之间的差异.对正弦电源作用下探测器的稳态响应进行了傅里叶级数展开,分析了基波和各次谐波幅值与入射信号强度之间的关系,研究结果为未来结合实验室大功率可调谐太赫兹源的实验研究奠定了理论基础.

Based on equations of fluid dynamics describing the concentration and the drift velocity of 2 DEG(two-dimensional electron gas) in the AlGaN/GaN heterostructure,the finite difference method was adopted to numerically solve the one dimensional nonlinear coupled system of partial differential equations with appropriate discrete time and space steps.The transient response and output direct current voltage(open circuit voltage between the drain-source terminals) of the field effect transistor detector under different intensity levels and frequencies of the incident terahertz(THz) signal was calculated,and the difference between the detector actual output(nonlinear response) and the existing small signal linear theory was quantitatively analyzed under the constant gate voltage.The detector steady-state response under the excitation of sinusoidal source was expanded by Fourier series,and the relationship between the amplitude of each harmonic and the intensity of the incident signal was analyzed.Research results will lay a theoretical foundation for future experimental research with powerful and tunable terahertz source at laboratory.