The Role of Deep Level States in the Optical and Electronic Properties of ZnSe Nanowires

摘要

II-VI semiconductor nanostructures are excellent candidates for next-generation optoelectronic devices, including tunable emitters. ZnSe nanowires can be fabricated easily, and show promise in blue emission applications. However, their practicality is limited by deep level defect states that inhibit their performance. The primary objective of this thesis is to relate the defect structure to the optical and electronic properties of ZnSe nanowires. To this end, a heat treatment procedure to improve the microstructure was identified, and measurements were performed before and after the treatment. Using low temperature photoluminescence spectroscopy, the dominant recombination mechanisms were related to the total defect concentration. The carrier concentration and electron mobility were determined by electron transport measurements on single nanowire transistors. The measured experimental data was used to construct a model describing the type, energies, and ionized fractions of relevant defects, and develop an understanding of how ZnSe nanowires can be tailored for optoelectronic applications.