Preparation And Properties Of Cu₂O-TFT Using Magnetron Sputtering Method

With the development of display technology, the oxide TFT has become a hot topic for resurch. The oxide TFT has some advantages, such as high transmittance、carrier mobility and can be prepared at low temperatures. However, the current focus on the oxide n-type TFT, such as IGZO-TFT ZnO-TFT. In contrast, there have been only a few reports on p-channel TFT because of lack of naturally p-type oxide semiconductors and difficulty in high-quality film growth. The P-type oxide TFT is not only limited to the applications in AMOLED and AMLCD, but also can be combined with n- type oxide TFT to form all oxide TFT CMOS and p-n diodes. Therefore, it is necessary to research the p-type Oxides. In this paper, Cu2 O films was prepared using magnetron sputtering and studied its properties; fabricated different thickness of Cu2O-TFT and studied their electrical properties. This thesis consists of the following three parts:1. The preparation of Cu2 O films. Cu disk(99.99%) was used as the sputtering target.The samples were deposited on glass substrates by magnetron sputtering at a working pressure of 1.8 Pa, oxygen and argon flow rates of 5 and 70 SCCM(standard cubic centimeter per minute), and sputtering power of 50 W, respectively. The effects of different substrate temperature on the structure and optical properties of Cu2 O films were researched.The results show that substrate temperature helps to improve the quality of thin film’s growth. The optical properties of different thickness of Cu2 O thin films were researched. The results show that the transmittance increases as the film thickness decreases.2. The preparation of Cu2O-TFT. The heavily doped p-Si was used as substrate and gate. SiO2 was used as insulating layer. Cu2 O thin film depoised by magnetron sputtering was used as semiconductor active layer. Al film depoised by electron beam evaporation was used as source and drain electrodes. The bottom-gate and top-contact p type Cu2O-TFT was fabricated successfully by the use of photolithography and lift-off process.The effects of different thickness of active layers on the Cu2O-TFT electrical properties were investigated. The results indicated that the performance of the TFT device increases with the increasing thickness of the active layer at the beginning,then tends to deteriorate. When the thickness of the active layer was 105 nm, field effect mobility and current on/off ratio was 6.1 × 10-2cm2/Vs and 4.5 × 102, respectively.3. The effects of heat treatment on the electrical properties of Cu2O-TFT were investigated.The results showed the active layer can effectively reduce defects in the film and thereby improve the electrical performance of the device. In the end, the stability of TFT was analyzed.