A Study On Equivalent Circuit Model For MgZnO Ultraviolet Detector And Transport Property Of MgZnO/ZnO Heterostructures

In recent years, with the development of the technology of optoelectronics, there are higher requests for the photoelectric detection system at the aspect of sensitivity, response speed and reliability. Therefore, optoelectronic integrated circuit(OEIC) has become the developing direction of the photoelectric detection system. Mg Zn O-based Metal- Semiconductor-Metal(MSM) ultraviolet(UV) detector is a core device of the ultraviolet detector system. It is of great importance to establish a precise and simple equivalent circuit model to improve the accuracy of circuit design and the success rate of optoelectronic integrated circuits. At present, the research about this area is a hot spot both in the optical communications field and the photoelectron device field. By the way, based on the two-dimensional electron gas(2DEG), Mg Zn O/Zn O MSM detectors with high quantum efficiency, response speed and optoelectronic integrated performance have gradually attracted the attention of the researchers. But it is limited to the material and characteristics of relevant devices. So it is necessary to do a further study on the transport properties of 2DEG.The main contents are organized as the following:1. On the basis of the combination of physical equations and device’s structures, a semi-analytical modeling which is suitable for describing the steady state and transient characteristics of the Mg Zn O-based UV MSM photodetectors is proposed. Internal photoconductive gain and the influence of the incident light energy on the device’s output characteristics are studied. The results show that internal photoconductive gain in Mg Zn O UV MSM photodetectors results in continued photoconductive effect, which brings serious negative impact on the response speed of the detector; When the energy of incident exceeds a certain threshold energy, the charge storage effect causes the output pulse to widen in the case of high-frequency and high-power. So we need a compromise between the energy of incident and the applied bias voltage on devices to minimize the effect for the applications of high-frequency and high-power.2. Quantum transport properties of 2DEG in undoped Mg Zn O/Zn O heterostructures with polarization charge effect have been investigated theoretically. Polarization roughness scattering(PRS), combining polarization charge and interface roughnessscattering, was proposed as a new scattering mechanism. PRS and background coulomb scattering together can well explain the changes of low-temperature electron mobility in Mg Zn O/Zn O heterostructures. The study indicates that polarization charges on the interface of Mg Zn O/Zn O HSs act not only as a carrier supply and a con?ning source but also as a scattering source for the position’s ?uctuations. PRS significantly reduces the low-temperature electron mobility when the electron density exceeded 1.0e11cm-2. To reducing the effect of PRS and improve the performace of Mg Zn O/Zn O MSM photodetectors, a smooth interface from the improved growth process and a separation between the 2DEG and the polarization charges may be the key improvement measures.This thesis provides some references for the design of high performance Mg Zn O-based UV detectors.