First Principle Study Of Electronic Structure And Optical Properties In Indium Iodide Crystal Containing Native Defects

With the development of the nuclear technique, semiconductor materials used fornuclear radiation detectors have a very widely prospect in various fields, such as nationaldefence and health care. Detectors that work with the chips made by Indium Iodide (InI)crystals have high energy resolution and high detective efficiency for γ-ray, due to theirwide band gap, large average atomic number, high resistivity, good carrier mobility-lifetime product. The detector made by InI crystal can be used and the data acquired can bestored in room temperature. These make InI to be one of the key new materials for roomtemperature nuclear radiation detectors.In this paper, the electronic structures and optical properties are calculated by thesoftware of Materials Studio which is based on first-principles calculations. And theinfluence of nuclear detection performance because of the native defects are studied.Firstly, the structures such as band gap, density of states, electron density differenceand optical properties like dielectric function, absorption, energy loss function andrefractive index of ideal InI were calculated by Materials Studio. The physical propertiesrelated to InI were obtained.Secondly, the structures of six possible native point defects (I and In vacancies, I andIn antisites, I and In interstitials) that maybe exist in the orthorhombic Indium iodide(InI)crystal are optimized and investigated by the first-principles calculations based on densityfunctional theory. The possibilities of these six native defects to be formed during thecrystal growth can be obtained through the calculated formation energy. The defect energylevels responding to every kind of native point defects and their effects on carrier transportare analyzed via density of states. The results show that dominant low-energy defect of Ininterstitial induces a recombination center which reduces the lifetime of the minoritycarriers and a deep hole trap which should capture the hole in the valence band to reducethe hole mobility-lifetime product.Finally, the optical properties of containing In interstitials and pure InI crystal arecompared and analyzed to clarify the influence on the optical properties via the introduction of In interstitials, and analyze the transition intensity changes with reasons ofelectrons between valence band to conduction band, further verify the influence on theelectronic structure by dominant low-energy defect of In interstitial.