tailieunhanh - Báo cáo hóa học: " Nano-structure fabrication of GaAs using AFM tip-induced local oxidation method: different doping types and plane orientations"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Nano-structure fabrication of GaAs using AFM tip-induced local oxidation method: different doping types and plane orientations | Ahn et al. Nanoscale Research Letters 2011 6 550 http content 6 1 550 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Nano-structure fabrication of GaAs using AFM tip-induced local oxidation method different doping types and plane orientations Jung-Joon Ahn1 Kyoung-Sook Moon2 and Sang-Mo Koo1 Abstract In this study we have fabricated nano-scaled oxide structures on GaAs substrates that are doped in different conductivity types of p- and n-types and plane orientations of GaAs 100 and GaAs 711 respectively using an atomic force microscopy AFM tip-induced local oxidation method. The AFM-induced GaAs oxide patterns were obtained by varying applied bias from approximately 5 V to approximately 15 V and the tip loading forces from 60 to 180 nN. During the local oxidation the humidity and the tip scan speed are fixed to approximately 45 and approximately pm s respectively. The local oxidation rate is further improved in p-type GaAs compared to n-type GaAs substrates whereas the rate is enhanced in GaAs 100 compared to and GaAs 711 respectively under the identical conditions. In addition the oxide formation mechanisms in different doping types and plane orientations were investigated and compared with two-dimensional simulation results. Introduction Atomic force microscopy AFM is considered as a promising tool to analyze and modify the nano-scaled structures and devices and thus AFM-based local oxidation AFM-LO process has been intensively investigated to fabricate and modulate nano-structures and devices such as field-effect transistors and single-electron transistors with various samples including metals semiconductors and even insulators 1 2 . The AFM-LO process is basically an anodic oxidation where the AFM tip and substrate act as the cathode and anode respectively. Thus by applying a negative bias to a conductive AFM tip an intense localized electric field is created at the substrate close to the tip and the .