Graduate / SOP for PhD program in optoelectronics [NEW]

The following is my SoP for PhD program admission. I wiil be very appreciated if anyone can help make suggestions and polish my essay. Thank you all.

Just at the moment I applied a power supply of ten volt, a reddish light radiated from the back surface of ITO-glass substrate. The light was dim, too weak to illuminate a small dark room, but strong enough to ignite my passion in the research on light emitting diodes (LEDs). My strong interest in LEDs originates from my sense of social responsibility: the conventional light sources should be replaced with novel high efficient LEDs from the viewpoint of saving energy and natural resources. I am determined to dedicate myself to the research in this field for the welfare of society and environment.

Born into a teacher's family, I was well-cultivated to be a self-motivated person thirsty for knowledge. During the four years at ABC University, I self-learned most fundamental and major courses, like College Physics, Solid State Physics, Electromagnetics, etc., and kept good academic records. However, my college experience was not limited to classes and textbooks. In my perception of knowledge, knowledge is just like tools. We gain nothing if we do not know how to utilize them. Thus while my peers were competing severely for the highest GPA, I was searching for any opportunity of practising. In the first semester, I passed the admission test (only 20 students passed the test among over 100 applicants in our department) and became a member of Electric and Electronic Science and Technology Innovation Center, where I could utilize knowledge learnt from textbooks to solve practical problems and I successionally took part in two electronic design contests in which the Intelligent Fan Control System and the Portable Digital Oscilloscope designed by my partners and I both won us good prizes (please refer to my CV).

Later, I found something more interesting than electronic designs: the research, when I interned as a research assistant, in my junior year, at the Institute of Optoelectronics and Integrated Information System, in the fabrication of Amorphous Silicon Solar Cells. There, I was in charge of amorphous silicon film deposition by PECVD, aluminum film deposition by E-beam evaporation, and the test and analysis of solar cells' performance. This experience endowed me a comprehensive training both in the theory of fundamental semiconductor physics and in the fabrication process of semiconductor devices, and probably the most important, it made me deeply realize the pivotal role solar cells are playing in energy conservation. My second research experience in college was in the Center of Computational Material Science, focused on the study of photo-catalyst properties of titanium dioxide by computational method, aiming at improving its photo-catalyst efficiency through energy band modification by doping various impurities. I exerted almost all my effort: reading papers, referring to books, discussing with professors, thinking independently and working hard, finally I found the best dopants with a co-doping configuration in titanium dioxide. My work was then summarized in my undergraduate thesis and won me a ward of "Outstanding Undergraduate". Through this research experience, my understanding in semiconductor was further deepened.

Motivated by the strong desire for higher academic achievement, I decided to pursue a Master degree. I was then admitted in the DEF, and majored in physical electronics. Only six days after graduation from ABC, I immediately went to DEF, participated, as a research assistant, in the project Photonic Crystal Vertical Cavity Surface Emitting Laser. In this project, my work focused on constructing an optical system to measure the photoluminescence of photonic crystal micro-cavities pumped by a 980 nm laser. The invisibility of the pump laser increased the difficulty of focusing the laser beam on the nanocavity. But I solved this problem by aligning a visible beam of 532 nm laser and the beam of pump laser in the same beam-path. Another difficulty was I had to be extremely careful about every optical component position and test various parameters to find out the lasing condition, since the photoluminescence was sensitive to the quantity of the pumping laser. But thanks to my patience, I finally found out the lasing condition after continuous trials and errors. This experience made me recognize that in research sometimes the Emotional Quality, like patience, is of the same importance as Intelligent Quality.

Now, I am engaged, as a chief researcher, in the project Colloidal Quantum Dots Light Emitting Diodes. This project is interdisciplinary and my research on this project is a little tough. For one thing, this field is new in our group. I do not have much reference to other senior graduates. For another, I have to synthesize the colloidal quantum dots by wet-chemistry method by myself, but I do not have any experience of chemistry synthesis. However, I challenged myself in synthesis. Fortunately, I eventually synthesized CdSe, PbS and PbSe nanocrystal quantum dots of different band gaps. This was just the first step. My ultimate goal is to fabricate light emitting diodes by virtue of these nanocrystal quantum dots. In order to cut the cost and simplify the fabrication process, I proposed a all-solution method, in which the electron transport layer, emitting layer, and the hole transport layer were all spin-coated with solutions. Now, light emitting diodes based on CdSe nanocrystal quantum dots fabricated on ITO-glass substrate are successful. My next step is to improve its efficiency and fabricate infrared LEDs based on PbS or PbSe on silicon substrate, in the hope of realizing silicon-integratable LEDs.

Undergraduate education equipped me with solid background in semiconductors and electronics, while graduate research trained me with a plenty of experimental skills and patient, persistent personalities. Now, I want to further my doctoral education in the Department of Electrical & Computer Engineering at your esteemed university, in the hope of doing research in the field of light emitting diodes, not solely because my interest has a good match with the research of many professors in ZZZ, such as Prof. XX and Prof. YY, , but also due to the word-class research condition provided by ZZZ. I am convinced that I am well-prepared for the study in the PhD program and I can make a great contribution in the field of LEDs if with the aid of your university.