二维场效应晶体管中基于跨导的热载流子分布光谱学
Hot-Carrier Distribution Spectroscopy by Transconductance in Two-Dimensional Field-Effect Transistors
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中文总结 AI 辅助
研究二维FET中跨导对载流子分布的探测，通过能量分辨传输框架将跨导分解，发现分布形状驱动项有异常峰值，校准后可约束热载流子参数，还能实现时间分辨扩展，确立二维FET为无需光学读出的分布函数光谱仪。
中文摘要 AI 辅助
场效应晶体管（FET）的跨导\(g_m = dI_D/dV_G\)传统上被视为载流子密度的代理。我们表明它实际上是载流子分布的光谱探针：因为\(g_m\)通过栅极电压导数\(\partial f(E)/\partial V_G\)对光谱电流\(j(E)\)加权并在能量上积分，所以它对\(f(E)\)的形状敏感，而不仅仅是其积分权重\(n\)。我们为二维（2D）FET开发了一个能量分辨传输框架，并在与栅极无关的光谱核近似下，将\(g_m\)分解为传统的密度调制项\(g_m^{(n)}\)和分布形状驱动项\(g_m^{(\alpha)}\)。后者是从测量的\(g_m\)中减去平滑的密度调制背景后得到的残余项，在栅极电压\(V_G^{\rm pk}\)处呈现出特征性的异常峰值。这个峰值在平衡传输中不存在，并且不能仅用载流子密度调制来解释。校准光谱核后，从标准的直流/锁定\(g_m\)扫描中提取的峰值位置和高度可以约束热载流子能量\(E_0\)、光谱宽度\(\sigma\)和产生阈值\(n_c\)，实现了载流子分布的稳态全电光谱学。一个可选的时间分辨扩展进一步从泵浦激发后的瞬态响应中恢复载流子弛豫时间\(\tau\)，确立了二维FET作为无需光学读出的分布函数光谱仪的地位。
英文摘要
The transconductance $g_m = dI_D/dV_G$ of a field-effect transistor (FET) is conventionally read as a proxy for carrier density. We show that it is instead a spectroscopic probe of the carrier distribution: because $g_m$ weights the spectral current $j(E)$ by the gate-voltage derivative $\partial f(E)/\partial V_G$ and integrates over energy, it is sensitive to the \emph{shape} of $f(E)$, not merely its integrated weight $n$. We develop an energy-resolved transport framework for two-dimensional (2D) FETs and, within a gate-independent spectral-kernel approximation, derive the decomposition $g_m = g_m^{(n)} + g_m^{(α)}$ into the conventional density-modulation term $g_m^{(n)}$ and a distribution-shape-driven term $g_m^{(α)}$. The latter, obtained as the residual after subtracting the smooth density-modulation background from the measured $g_m$, exhibits a characteristic anomalous peak at a gate voltage $V_G^{\rm pk}$. This peak has no counterpart in equilibrium transport and \emph{cannot be explained by carrier density modulation alone}. With the spectral kernel calibrated, the peak position and height -- extracted from standard DC/lock-in $g_m$ sweeps -- constrain the hot-carrier energy $E_0$, spectral width $σ$, and generation threshold $n_c$, realizing a steady-state, all-electrical spectroscopy of the carrier distribution. An optional time-resolved extension further recovers the carrier relaxation time $τ$ from the transient response following a pump excitation, establishing the 2D FET as a distribution-function spectrometer that requires no optical readout.
