摘要
We report the room temperature resonant tunneling and negative differential resistance(NDR)effects in a self-assembled Si quantum dot(Si-QDs)array.The double-layer structure of Al/SiO_(2)/Si-QDs/SiO_(2)/p-Si substrate is fabricated by layer-by-layer deposition and in situ plasma oxidation in a plasma-enhanced chemical vapor deposition(PECVD)system.Obvious NDR effects are directly observed in the current-voltage characteristics,and similar peak structures at the same voltage are also identified in the capacitance-voltage characteristics.Both of them are attributed to the resonant tunneling and charging dynamics in the Si-QD array.Moreover,the major features,such as the scan-rate and scan-direction dependences of the peak structure,are investigated,and the underlying mechanism is found to be quite different from that of a quantum well structure.Based on a master-equation numerical model,the resonant tunneling and charging dynamics together with the unique features can be satisfactorily explained and reproduced.
报道了自组装Si量子点(Si-QDs)阵列在室温下的共振隧穿及其微分负阻特性.在等离子增强化学气相沉淀系统中,采用layer-by-layer的淀积技术和原位等离子体氧化方法制备了Al/SiO_(2)/Si-QDs/SiO_(2)/Substrate双势垒结构.通过原子力显微镜和透射电子显微镜检测,证实所获得的Si-QDs阵列中Si量子点平均尺寸为6nm,并具有较好的尺寸均匀性(小于10%).在对样品的室温I-V和C-V特性的测量中,直接观测到由于Si量子点中分立能级而引起的共振隧穿和充电效应:I-V特性表现出显著的"微分负阻特性(NDR)";而CV特性中也同样观测到位置相对应、结构相似的峰结构,从而证实了I-V和C-V特性中的峰结构都同样来源于电子与Si量子点阵列中分离能级之间的共振隧穿和充电过程.进一步研究发现,Si量子点阵列中共振隧穿和NDR特性所特有"扫描方向"和"速率"依赖性及其机制,与量子阱的情况有所不同.通过所建立的主方程数值模型,成功地解释并重复了Si量子点阵中共振隧穿所特有的输运特性.
基金
国家重点基础研究发展规划(批准号:2001CB610503)
国家自然科学基金(批准号:90101020,90301009,10174035)资助项目
