镶嵌在超薄SiO_2层中的纳米硅的库仑阻塞现象

采用等离子体氧化和逐层 (layer by layer)生长技术在等离子体增强化学气相沉积 (PECVD)系统中原位制备了 Si O2 /nc- Si/Si O2 的双势垒纳米结构 ,从 nc- Si薄膜的喇曼谱中观察到结晶峰 ,估算出该薄膜的晶化成分和平均晶粒尺寸分别约为 6 5 %和 6 nm.通过对该纳米结构的电容 -电压 (C- V)测量 ,研究了载流子的隧穿和库仑阻塞特性 .在不同测试频率的 C- V谱中观测到了由于载流子隧穿引起的最大电容值抬升现象 .通过低温低频 C- V谱 ,计算出该结构中 nc- Si的库仑荷电能为 5 7me V.

Coulomb Blockade Effect of Carriers in nc-Si Embedded in Ultrathin SiO2 Films

The nanocrystalline silicon (nc-Si) based double oxide barriers structures are fabricated in-situ by plasma oxidation and layer by layer technique in a plasma enhanced chemical vapor deposition (PECVD) system.The average grain size of nc-Si in this structure is about 6nm that is obtained from Raman spectrum.The nc-Si is firstly deposited on the tunneling oxide layer (2nm) and then oxided to form the gate oxide layer (5nm).The maximum capacitance of this structure at negative bias increased with decreasing frequency,which reflected the tunneling of holes between the nc-Si and the substrate through ultrathin tunneling oxide.Furthermore,two peaks in the low frequency capacitance curves,corresponding to the resonant tunneling of electrons into nc-Si,are observed.From the peaks in the low frequency (1kHz) C-V curves,the coulomb blockade energy (57meV) is estimated.