Fabrication of Resonant Tunneling Diode by Atomic Layer-by-Layer Epitaxial Growth of Si-Ge-C-N System

在本工作中，为了创造一种具有新特性的原子控制材料，研究了在Si（100）和Ge（100）上形成N和C原子层，随后在N/Si（100）或C/Ge（100）上进行Si外延生长，以及Si-Ge-C-N系统的原子控制共振隧道二极管的制造。在SiH_3CH_3在Ge（100）上的低温原子级表面反应中，发现Si和C的单原子层自限形成，Si（100）上也有N原子层形成。在低于500℃的生长温度下，在1 / 10 C/Ge（100）原子层和1 / 2 N/Si（100）、Si/原子层上实现了Si的外延生长。在Si/N/Si结构中，掺入的N原子被限制在约1nm厚度内，最大浓度在5x10^<21>cm^<-3>以上。发现抑制Si_3N_4结构对于获得高质量的高氮浓度的氮原子层掺杂Si膜是非常重要的。随着Ge分数的增加，热处理过程中Si/SiGe/Si（100）异质结构的互扩散速度加快，但界面处存在1 / 10 （7x10^<13>cm^<-2>）的C抑制了Si/Ge异质界面处的互混。这些结果对实现高质量的自动控制异质结构器件具有重要意义。利用上述结果，将原子层N掺杂应用于SiGe谐振隧道二极管的双Si势垒，测量的电学特性表明，与未掺杂N的参考二极管相比，隧道电流密度明显受到抑制。这些结果表明，N掺杂可以调制Si的电子能带结构，并且原子层掺杂技术对于控制共振隧道特性是有效的。

In the present work, in order to create an atomically controlled materials with a novel properties, atomic-layer formation of N and C on Si(100) and Ge(100), subsequent Si epitaxial growth on the N/Si(100) or C/Ge(100), and fabrication of an atomically controlled resonant-tunneling diode of Si-Ge-C-N system have been investigated. In a low-temparature atomic-order surface reaction of SiH_3CH_3 on Ge(100), it is found that single atomic layers of Si and C are formed self-limitedly, as well as N atomic layer formation on Si(100). The Si epitaxial growth on one tenth atomic layer of C/Ge(100) and a half atomic layer of N/Si(100), Si/have been achieved at the growth temperatures below 500℃. In the Si/N/Si structures, the incorporated N atoms are corfined within about 1nm thickness and the maximum concentration is above 5x10^<21>cm^<-3>. It is found that suppression of Si_3N_4 structure is important to obtain a high quality N atomic-layer doped Si film with high N concentration. It is also found that interdiffusion at Si/SiGe/Si(100) heterostructure during thermal treatment proceeds faster with increase of Ge fraction, although the intermixing at Si/Ge heterointerface is suppressed by the existence of one tenth (7x10^<13>cm^<-2>) of C at the interface. These results are quite important to realize high-quality atomically-controlled heterostructure devices. By using above results, atomic-layer N doping is applied to double Si barriers of SiGe resonant tunneling diode, and measured electrical characteristics show that tunneling current density is obviously suppressed compared to the reference diode without the N doping. From these results, it is suggested that an electronic band structure of Si can be modulated by the N doping, and that the atomic-layer doping technique is effective for control of resonant tunneling characteristics.