Investigate On The Properties Of Gan Films Deposited On FTO Conductive Glass Substrates At The Low Temperature

GaN is direct band-gap (3.39eV at300K) semiconductor, which is widely used in the field of light-emitting diode (LED) since1990s. As the second generation semiconductor material after silicon, GaN, with excellent properties, e.g., high thermal stability, low dielectric constant and high electron saturation drift velocity, is always the hot topic among nitric compounds. GaN based LED and laser diode have been broadly used. Own to its high sound wave velocity and outstanding piezoelectricity properties, GaN is also the ideal material for high-frequency level SAW. The substrate affects the quality of growth films on it directly. So far, the films of GaN are mainly grown on foreign substrates, for instance, on α-Al2O3, SiC, ZnO and Si wafers. The most used α-Al2O3surface limits the development of GaN based photodevices due to its expensive cost, hard to be dissociated and to grow large films on it. As an alternative substrate, FTO-glass improves the electronic properties of devices. On the other hand, it can be used as the electrode directly, which solved the current-crowding effect, raising efficiency of LED further. Most important, it is cheaper material by depositing a layer conductive film on ordinary glass, comparing with other substrates. Previously, man tried to transfer the GaN films produced on α-Al2O3substrate onto transparent conductive electrode. But it results in a low yield product due to its hard technologic requirement. However, if the high-quality GaN films could be synthesized on FTO-glass directly, it would improve devices’ the electronic properties and meet the needs of electrode, without complex technologic proceedings. Generally, metal substrates are all melt more or less due to high temperature required for GaN film deposition, lowering the quality of GaN films. Therefore, the deposition temperature can be too high for GaN film growth on FTO-glass. In this thesis, Electron cyclotron resonance-plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD) is used to deposit GaN film, stimulating the active of deposited particles and lowering the temperature greatly. Highly c shaft preferred orientation GaN film is produced on FTO substrate with TMGa and high-pure N2as precursors at low temperature. Using reflection high energy electron diffraction, X-ray diffraction and atomic force microscope, we investigated the effects on the quality of GaN films produced on FTO-glass substrate by the rate of TMGa flow and the temperature of substrate and obtained the appropriate technologic parameters. The experimental results indicate that the quality of GaN film is better crystallized at500℃, with1.7scem flow of TMGa and100scem flow of N2on fixing other parameters condition.