Measurement And Theoretical Simulation Of The Schottky Barrier Region Of ZnO Nanobelt/Nanowire

With the development of science and technology, the requirement for the future devices is smaller, higher integrated density and lower energy cons?mption. Nano devices instead of micron devices will be the trend of the development. One-dimensional nano semiconductor material can not only be used as a component element, but also can be used as a conductor of the connector element, so it is widely used to construct the electronic device. One-dimensional ZnO nanomaterials not only has good chemical stability, mechanical stability and larger specific surface area, but also has excellent photoelectric properties and piezoelectric properties, with a result that it has been widely used in environmental detection, electronics and new energy fields.The contact of Metal electrode and semiconductor material is inevitable problems in building components. The properties of contacts, especially the schottky barrier contacts, play a critical role for device performance. The study of the block schottky barrier has been very mature, and the theory conform well with experiment. However, when the macroscopic potential barrier model is used to explain the schottky barrier of the nanometer size contact area, we have found that the difference between theoretical calculation and experimental results are greatly. This is mainly due to nano device contact area is very small, while the traditional model is based on the ass?mption of an infinite plane. In addition, schottky barrier is affected by the type of contact. Two contact modes of one dimensional nano semiconductor material and electrode include horizontal contact and axial contact. Because of the limitation of process conditions, the common way of contact for one dimensional nano device are horizontal contact. The contact surface parallel to the long axis direction of nanobelt /nanowires. When the bias is applied to the schottky device, the carrier can not only be transported along the axial direction, but also can be transported in the vertical direction. Although one-dimensional nano schottky barrier has been widely studied, most of them are to extract effective height of the schottky barrier. The transport characteristics of schottky devices not only controlled by the barrier height, but also be impacted by potential barrier structure. Researching on the structure of the one-dimensional schottky barrier is conducive to our better understanding of the transport mechanism of one-dimensional schottky device, at the same time it can provide guidance for us to design schottky devices with excellent properties.In this paper,firstly, the ZnO nanobelts/nanowires with uniform morphology and good crystallinity were prepared by chemical vapor deposition(CVD). Then, the morphology, crystallinity and crystal structure of ZnO nanobelts / nanowires were characterized By SEM, XRD and PL and so on. The results showed that These nanobelts /nanowires have a good crystallinity, six wurtzite structure and high yield. The micro probe assisted transfer to build a single ZnO nanobelt/nanowire device and test the basic properties of devices, the I-V curves showed that ZnO nanobelts/nanowires and electrode formed asymmetric back-to-back Schottky contact. In addition, the simulation software calculation process and the physical formula were introduced briefly,and a two-dimensional schottky device structure model was established.Secondly, we measured the potential of the schottky contact region of the ZnO nanobelt /nanowire device with different carrier concentration by using the system for the probe measurement. The measurement results show that the partial pressure of the resistance of schottky devices with different concentrations increases with the increase of reverse bias voltage. When the carrier concentration is higher,the depletion layer is smaller. when the carrier concentration was low, We have found that the device of lateral pinch off effect; and when the reverse bias increases we have also found that the depletion layer transverse exhausted will enlargement to the axial. At the same time, the ATLAT simulation software is used to simulate the above problems with the structure model of two-dimensional schottky device, and the simulation results are in good agreement with the experimental results. The simulation results show that the electric potential distribution along the axial direction is not uniform along the axial direction of the electrode, and the degree of depletion in the transverse direction is different along the axial direction of the schottky contact.Finally, we use the semiconductor simulation software to analyze the I-V curves of the tunneling model and the mobility model. In the case of the lateral not depleted, the I-V curve of the tunneling model under upward bending, but I-V curve of the migration rate model under the downward bending. In the tunneling model, the I-V curve is more abundant because of the different distribution of the current density under different bias voltage. In addition, we investigated the effects of different carrier concentration, electrode length and barrier on the transport properties of the devices. It showed that the tunneling effect was more likely to occur under high carrier concentration, and the electrode length had less effect on the transport of the device under the tunneling model. At the same time, the length of the electrode was longer, the lateral pinch off effect was more obvious. Barrier effects on the devices of the two models are very large. The current increased exponentially with the decreased of the barrier height.