July 23, 2015
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Meet Juan Diaz Leon: future materials scientist

Carrie L Martin, martin59 [at] llnl.gov, 925-424-4715

Editor's Note: This is one in a series of articles highlighting the diverse group of Lawrence Livermore National Laboratory summer students.


The Lawrence Livermore National Laboratory (LLNL) student internship program is designed to allow students to engage in work-study employment opportunities in relevant science, technology, engineering, mathematics (STEM) and administrative fields during the summer academic break. This year, LLNL is proud to welcome more than 600 students from universities nationwide and around the world.  

Introducing Juan Diaz Leon…

Full name: Juan Jose Diaz Leon

Hometown:  Granada, Spain

University attending/educational background: Currently pursuing a doctorate in electrical engineering at the University of California, Santa Cruz. In 2013, I received a master’s of science degree in electrical and telecommunication engineering from the University of Granada in Spain, where, as an exchange student, I was able to perform the research at the University of California, Santa Cruz.

Major: Electrical engineering

Graduation year: 2017

LLNL Directorate you are working in: Materials Science Division (MSD) in the Physical and Life Sciences Directorate

What interested you in pursuing a summer internship at the Laboratory?

Going to grad school, I thought it would be a great opportunity if I could get experience at a national laboratory. My dissertation is focused on the design, growth and characterization of optical materials, so LLNL seemed to be a great fit for it. I decided to contact leading researchers on the fields I work on, with the hope that I could get a chance to work with them during the summer.

What are you working on at the Laboratory?

I am working on the design of broadband, wide-angle antireflection coatings. In other words, I am trying to capture as much light as possible from every angle and every wavelength I can. In order to do that, I am running simulations using COMSOL multiphysics modeling software to test and improve different designs. The designs will then be created with the state-of-the-art deposition and fabrication tools here at the Lab.

What do you enjoy most about interning at the Laboratory?

I really enjoy that senior scientists are able to do research on a daily basis. It is very exciting and impressive to me to see how individuals with so many responsibilities still have time to run experiments, and despite their busy schedules, they are always willing to hear me and help me. Apart from that, the Lab has great capabilities in so many scientific aspects: theoretical modeling, computation, growth, fabrication, characterization, testing, etc. It is a very collaborative space where unimaginable projects can be solved.

What have you learned (or are learning) that has made a difference to you?

Because of the specifics of my project, I need to run simulations that require a lot of computational power. I am learning how to simplify my models and I also get to use some of the cluster computers, which is something that I had not been able to do in the past. This allows me to simulate and optimize designs at a level that will be much closer to reality.

Where do you see yourself after graduation? What is your dream job?

After graduation I see myself in a research position in industry, in academia or at a national laboratory. My dream job is working as a materials scientist. I want to keep actively doing research and making science so that we can move forward in the photonics world. I like to be involved in all the different aspects of a project from start to finish, which includes design, modeling a structure and optimizing it, growth, creating the actual structure and characterization and studying the properties.

Who/what has inspired you to pursue an education and career in a STEM field?

I've always been very interested in how things work, not only at the surface, but at a deeper level, which is why I became an engineer. During my research, I realized that the scientific aspect of the problems I solved is what really interested me and got my attention. So, I used my engineering and physics background for optics and photonics. Sometimes when I hit a wall or problems get very complicated, I wonder why I chose this career. But I know that I wouldn’t be happier doing anything else. 

What has been your biggest challenge to overcome?

When I was writing my master’s thesis on a deposition tool called metal organic chemical vapor deposition, a faulty alarm system caused back flow in our reactor, filling all the clean lines with precursors, destroying a lot of electronics and vacuum equipment. Figuring out what had gone wrong and solving the problem was a daunting task that took me and another graduate student several months. Due to our diligence, we became very familiar with the process and learned every aspect of it. That was also the reason why I decided to pursue a Ph.D. It was very exciting to apply my knowledge and solve real problems.

What do you consider to be your biggest accomplishment so far?

That is for others to say. However, I think that my time working on Advanced Research Projects Agency-Energy (ARPA-E) project was very enriching. The project was unfortunately canceled prematurely, but we made very cool science. I hope that we can use some of it in the future to increase the efficiency of renewable energies, especially with solar power and LEDs.

As a college student, what is the most important lesson you have learned?

Through school, I learned that it is important to understand the problem you are trying to solve before trying to find a solution for it. I also learned that proactivity and teamwork are key if you want to succeed in any difficult endeavor. When you finish college, you might not know the answer to a question straight away, but you probably know how to look for it. In my experience, graduate school is more about problem solving. It challenges you to figure out how to solve problems that have never been attempted before.

What advice would you give a high school student?

I would advise high school students to follow their dreams. Try to find something that they love and pursue that career. It might take a couple of attempts to realize what they really like, but that’s part of the process. Failing is one of the best ways to learn. I always get the most valuable experiences when something goes wrong and I need to find a solution.

What do you like to do in your spare time? What are your hobbies?

I love the outdoors. The only way I am able to stay in the lab or in front of a computer when I'm at work, is because I am so active outside of work. I like to bike, surf, sail, run and hike. I also like to travel when I can.

What is next for you/what are you looking forward to?

I have more than a year left in grad school. I am going back to the University of California, Santa Cruz this fall to keep working on my doctorate. After that, I am not sure. Only time (and research results) will tell.



To learn more about summer internships and the Laboratory’s scholar programs, visit the scholars@llnl website. https://scholars.llnl.gov/ .

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