Semiconductor Research

Have you ever heard of Moore's law? Gordon Moore made an observation in 1965 that the number of transistors on a microchip roughly doubles every two years. This pattern has stayed very consistent for the last sixty years. Adding more transistors to a microchip allows for improved processing speed and decreased cost per function, an ever-important quality in our rapidly growing network. This requires constant innovation and sharing of information.

In June 2024, I was accepted into Krishnamoorthy research group. This group, led by Professor Sriram Krishnamoorthy, seeks to expand the capabilities of ultra-wide band gap (UWBG) semiconductors - particularly concerning GaN and ß-Ga2O3). These types of semiconductors have a higher energy requirement for electrons to jump from the valence band to conduction band, which makes them more capable at operating in higher temperatures and voltages. A higher power rating is preferable for semiconductors due to improved computing power, which makes for even more efficient electronics. Several semiconductor candidates have been compared on what is called a Baliga Figure of Merit, which essentially plots the power rating of these semiconductors against each other (lower right means higher power rating).

Baliga Figure of Merit for research semiconductors

Despite c-BN (cubic boron nitride) being at the bottom right, silicon is currently the most manufactured semiconductor. Power rating is a great metric for choosing semiconductors, but there are several others to consider. To start, these are projected power ratings, not tested power ratings. Many of these materials exist further top-left from their projected lines, which indicates a need for stronger research for semiconductors. Silicon is much more accessible than the other materials, which factors into cost. Some materials, such as diamond, are harder to manufacture into specific dimensions than silicon. Other materials, such as ß-Ga2O3, have much lower thermal conductivity than the other materials, which limit how much energy it can withstand.

As mentioned earlier, the UWBG semiconductors Krishnamoorthy group specializes in are GaN and ß-Ga2O3. The work ranges from fabricating semiconductors with multi-beam epitaxy and metal-oxide chemical vapor deposition (various methods for constructing microscopic semiconductors), to electrical characterization of these devices and comparing to other research groups. The results of the research are discussed amongst the group and scrutinized for improvement. Most of the students involved are earning their Ph.D in materials, specifically in electronics. When I entered, I was an undergraduate mechanical engineer who happened to share an interest in their field. My final undergraduate year was spent shadowing these students in electronic characterization, attending their meetings, and presenting a few searched articles about specific semiconductor models/results. This helped me become more adept in the field of electronics, despite it being outside of my studies as a mechanical engineer.

Now entering my first year as a graduate student, I am hoping to contribute more to the group's studies than the previous year. I am in the process of discussing a year-long project with Prof. Krishnamoorthy where I can combine my education as a mechanical engineer with one of the previously mentioned limiting factors of ß-Ga2O3 and GaN: thermal conductivity. By improving how well the fabricated semiconductors can manage heat transfer, the semiconductors will be able to endure a higher voltage before breaking down. This will help move the tested performance of these semiconductors closer to the projected rating in Baliga Figure of Merit, potentially motivating more electronics to be built with ß-Ga2O3 and GaN. I will clarify my project more when I meet with Prof. Krishnamoorthy in the near future and update as much information as I am working for the research group and not independently (I will assume the research is classified unless approved otherwise). However, I feel it is important for anyone to know what work I am currently doing and what I hope to achieve with this project.