Choi Haeju, Li Jinshu, Kang Taeho, Lee Sangmin, Hwang Euyheon, Lee Sungjoo
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SSKU), Suwon 16419, Korea.
Department of Nano Science and Technology, Sungkyunkwan University, Suwon 16419, Korea.
Nanoscale. 2024 Oct 24;16(41):19469-19476. doi: 10.1039/d4nr01689k.
The impact ionization process offers advantages in achieving low-power and high-speed switching in transistors and also provides high internal gain for photodetectors. We investigate the density dependence of both electron- and hole-initiated impact ionization in WSe. We observe a record-low critical electric field for impact ionization and a large multiplication factor in WSe when the impact ionization is initiated by holes, particularly near a charge-neutral point. As the carrier density increases, the impact ionization decreases, which is attributed to the increase in Fermi energy and the weakening of the carrier-carrier interaction by increasing the screening effect. To understand the role of screening effects on the impact ionization, we examine the carrier scatterings of several scattering sources and the rate of change of the channel current with respect to the drain source voltage, Δ/Δ. We obtain the optimal conditions for impact ionization and apply these findings to fabricate avalanche photodetectors (APDs). This study proposes that the performance of low-power transistors or APDs, utilizing impact ionization, can be enhanced under optimized conditions by examining and controlling specific external parameters.
碰撞电离过程在实现晶体管的低功耗和高速开关方面具有优势，同时也为光电探测器提供高内部增益。我们研究了WSe₂中电子和空穴引发的碰撞电离的密度依赖性。我们观察到，当碰撞电离由空穴引发时，特别是在电荷中性点附近，WSe₂中碰撞电离的临界电场创历史新低，且倍增因子很大。随着载流子密度增加，碰撞电离减少，这归因于费米能量的增加以及通过增强屏蔽效应使载流子-载流子相互作用减弱。为了理解屏蔽效应在碰撞电离中的作用，我们研究了几种散射源的载流子散射以及沟道电流相对于漏源电压的变化率ΔI/ΔV。我们获得了碰撞电离的最佳条件，并将这些发现应用于制造雪崩光电探测器（APD）。本研究表明，通过检查和控制特定外部参数，在优化条件下利用碰撞电离的低功耗晶体管或APD的性能可以得到提升。
