Gao Anyuan, Lai Jiawei, Wang Yaojia, Zhu Zhen, Zeng Junwen, Yu Geliang, Wang Naizhou, Chen Wenchao, Cao Tianjun, Hu Weida, Sun Dong, Chen Xianhui, Miao Feng, Shi Yi, Wang Xiaomu
National Laboratory of Solid State Microstructures, School of Physics, School of Electronic Science and Engineering, Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing, China.
International Centre for Quantum Materials, School of Physics, Peking University, Beijing, China.
Nat Nanotechnol. 2019 Mar;14(3):217-222. doi: 10.1038/s41565-018-0348-z. Epub 2019 Jan 21.
Impact ionization, which supports carrier multiplication, is promising for applications in single photon detection and sharp threshold swing field effect devices. However, initiating the impact ionization of avalanche breakdown requires a high applied electric field in a long active region, which hampers carrier multiplication with a high gain, low bias and superior noise performance. Here we report the observation of ballistic avalanche phenomena in sub-mean free path (MFP) scaled vertical InSe/black phosphorus (BP) heterostructures. We use these heterojunctions to fabricate avalanche photodetectors (APDs) with a sensitive mid-infrared light detection (4 μm wavelength) and impact ionization transistors with a steep subthreshold swing (<0.25 mV dec). The devices show a low avalanche threshold (<1 V), low noise figure and distinctive density spectral shape. Our transport measurements suggest that the breakdown originates from a ballistic avalanche phenomenon, where the sub-MFP BP channel support the lattice impact ionization by electrons and holes and the abrupt current amplification without scattering from the obstacles in a deterministic nature. Our results provide new strategies for the development of advanced photodetectors via efficient carrier manipulation at the nanoscale.
支持载流子倍增的碰撞电离在单光子探测和尖锐阈值摆幅场效应器件中具有应用前景。然而，引发雪崩击穿的碰撞电离需要在长有源区中施加高电场，这阻碍了具有高增益、低偏置和优异噪声性能的载流子倍增。在此，我们报告了在亚平均自由程（MFP）尺度的垂直InSe/黑磷（BP）异质结构中观察到的弹道雪崩现象。我们利用这些异质结制造了具有灵敏的中红外光探测（波长4μm）的雪崩光电探测器（APD）以及具有陡峭亚阈值摆幅（<0.25 mV/dec）的碰撞电离晶体管。这些器件显示出低雪崩阈值（<1 V）、低噪声系数和独特的密度谱形状。我们的输运测量表明，击穿源于弹道雪崩现象，其中亚MFP的BP沟道通过电子和空穴支持晶格碰撞电离，并且电流在没有来自障碍物的散射的情况下以确定性方式突然放大。我们的结果为通过纳米尺度的高效载流子操控开发先进光电探测器提供了新策略。
