Nanocrystal Coupling Influences on Electrical Properties of PbSe Nanocrystal Array

• Main Author: 柯凱廸
• Other Authors: Jian, Wen-Bin
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/57697265906903808936

碩士 === 國立交通大學 === 電子物理系所 === 100 === The electron transport in PbSe nanoparticle arrays at various strengths of inter-particle coupling is studied from temperature behaviors of current-voltage curves at a temperature range between 80 and 300 K. In this study, PbSe nanoparticles with an average diameter of 14.6 nm were attracted by dielectrophoresis and they form an array between two nano-scale electrodes patterned by electron beam lithography. The as-fabricated PbSe nanoparticle-array devices were highly insulating. In order to raise the inter-particle coupling, thermal annealing was employed to fine tune the inter-particle distance. Under different annealing conditions, we find that the resistances of the samples decrease with an increase of the annealing temperature. We argued that the charging energy and quantization effects are negligible small in our case so we used thermal activation of nearest neighbor hopping and Mott’s variable range hopping theories to explain our experimental results at high and low temperatures. Through scrutinizing all fitting parameters, we discovered a crossover from localized regime to extended regime which is possibly manipulated by the inter-particle coupling strength. In the localized regime, the activation energy at high temperature is used for an excitation from the Fermi level to the 1S state of PbSe nanopaticles for hopping transport between nanoparticles. In the extended regime, the activation energy of the sample at high temperature is half of the case in the localized regime, which evidences the absence of excitation energy.