Growth Study Of GaN/ZnO Films On Si Substrate And Lifetime Test Of LED Devices

GaN based semiconductors manifest a wide direct band gap, and have been demonstrated a large potential for applications in Opto-electronic domains. For all these applications, the Ⅲ-Ⅴ nitride layers are usually grown on sapphire or on silicon carbide substrates. However the development of some of these applications on silicon (Si) substrates has obvious technological advantages, including the low cost, large-scale availability, good thermal and electrical conductivities and the feasibility of removing the Si substrates with wet etching. There has been a great progress in depositing GaN on the Si substrate in the several years. Recently the GaN LED on Si substrate produced by our laboratory have almost same properties comparing the LED on sapphire substrate. Many literatures have report the lifetime test of GaN LED on sapphire, but there is not any report of the lifetime test of GaN LED on Si substrate. The lifetime of LED may be of 105 hours theoretically, and it might not be practical to gather date for long periods of time. Therefore, in this thesis, we introduce an accelerated current lifetime test method to calculate the lifetime of bule and green GaN LED on Si substrate produced by our laboratory. Some significative resultes are following as:1. Accelerated aging tests of GaN blue light-emitting diodes on Si substrate under current stress were investigated. When the drive current is higher, the main wavelength of LED is more bigger. That is because with the high drive current, chip will produce a great deal of heat which makes the diffusion of Si on N type GaN and Mg on P type GaN into the radiation layer of InGaN, then the band gap wide will diminish, the main wavelength will red shift.2. When the drive currents are low, the working voltage of GaN blue LED on Si substrate has almost no change, but when the drive currents are high, the working voltage will became higher along with the increase of time. It is due to the too high temperature that will destroy the ohmic contact of LED.3. According to the lifetime test of LED, the lifetime of GaN bule LED on Si substrate is...