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Preparation And Characterization Of Mgzno Films Study

Posted on:2007-09-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:X J ZhangFull Text:PDF
GTID:1118360185484247Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
In recent years, much attention has been given to wide band gap semiconductors for the wide uses in blue and ultraviolet light emitters and detectors. The materials for emitting blue light, such as GaN and ZnSe, have been fabricated, but they have obvious shortcomings. A mass of defects appear in ZnSe laser at high temperature, so its lifetime is very short. For achieving GaN, the equipment is expensive, substrate is lacking and growth is difficult.The crystal structure and lattice constant of ZnO are similar to those of GaN. An outstanding feature of ZnO is its large excitonic binding energy of 60 meV leading to the existence and extreme stability of excitons at room temperature, which should allow efficient excitonic lasing mechanism operate at room temperature. This facilitates to achieve low threshold lasers.There are two important conditions to prepare ZnO-based devices:1. p-ZnO. For ZnO, n-type conductivity is relatively easy to realized via excess Zn or with Al, Ga, or In doping. With respect to p-type doping, ZnO displays significant resistance to the formation of shallow acceptor levels.2. Band gap engineering. In the fabrication of optoelectronic devices, modulation of the optical constant and band gap energy of the constituent layers while keeping their lattice constant close to each other is important for constructing appropriate heterostructures. MgZnO has been considered as an appropriate ternary alloy system that can construct an efficient heterojunction with ZnO. The band gap energy of MgZnO can increase from 3.3 to 7.9 eV by increasing the Mg content. Therefore, MgZnO thin films can be used not only as barrier layers for ZnO active layer, but also directly as an ultraviolet light emission material.There have been some reports on properties of MgZnO thin films, but most of the films have been prepared by pulsed laser deposition (PLD), molecular beam epitaxy (MBE), and metalorganic vapor-phase epitaxy (MOVPE) and their growth temperature is very high (500-650℃).In this dissertation, the MgZnO thin films have been prepared by radio frequency...
Keywords/Search Tags:wide band gap semiconductors, radio frequency magnetron sputtering, MgZnO films, structure properties, optical properties
PDF Full Text Request
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