Graduate / 'My research work' - Help: sop in EE major [4]

My quest has been to become a top researcher in microelectronics and photonics. The training I have received at XXX has not only helped me establish a solid knowledge foundation, but also offered me many opportunities to participate in various lab projects which further improved my research ability.

My first project in XXX was to characterize the optical characteristics of AlGaN-based deep-ultraviolet light-emitting diodes (LEDs). I applied pulsed injection with different duty cycles to distinguish the thermal and non-thermal factors affecting the LED performance. I found that thermal effects due to self-heating can be largely eliminated by pulsing the LEDs with a tiny duty cycle below 2%, and that the quantum efficiency of the LEDs increased monotonically at low currents and attained a low saturated value at high currents. From this project, I not only became familiar with the physical mechanics of LEDs but also gained a lot of hands-on experience. I managed to set up by myself a testing system to record the electroluminescence intensity and spectra of the LEDs by using an Ocean Optics fiber-optic spectrometer. Based on the experiment result from this project, I published a journal paper on Physica Status Solidi (a).

My recent research work concentrates on Indium Tin Oxide (ITO) contacts to LEDs. The final target is to achieve good ohmic contact on LEDs with a comparatively high transmission. To fulfill this aim, I divide the whole project to several steps. First, I studied the charatericteristics of single film of ITO on quartz wafer. Then I deposited an ITO layer on p-GaN and optimized the resistance and transmittance. This was the most important step. In order to form ohmic contact and to minimize the contact resistance, I tried different ways, such as introducing a very thin interlayer of Ni between ITO and p-GaN, bombarding the surface of p-GaN and depositing Ni-doped ITO on p-GaN with sputtering. By these means, the resistance was greatly reduced while the transmission remains around 90% at 600C in the visible range of wavelength. The last step is to put ITO on LEDs, which is on going. At the same time, I have the chance to learn how to fabricate LED step by step, from mesa to p-metal. I learned a great deal from this project. My ability to design and conduct an experiment was greatly enhanced. For each experiment, I prepared a research plan to determine the optimum conditions. Moreover, I gained a great deal of work experience in a cleanroom and can manipulate all the facilities in our cleanroom.

As I learn more about my field, my desire to make progress in microelectronics and photonics is stronger. I would very much like to pursue my goal at a top university where I am allowed to work more effectively and creatively. XXX is my dreaming choice. Besides well equipped laboratories and an excellent fame, I was more attracted by the scientific prowess of the faculty, as demonstrated by their publications. I would like to apply for a Ph.D. degree in the research area of Microelectronics and Nanotechnology, which is highly related to my background. What is more, I will have chance to conduct experiments in the lab. The feeling is so great to create something new and meaningful through experiments. It motivates me to keep thinking and trying different methods to achieve my research goals.