| Research Abstract |
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.
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