Karen Dowling: Exploring semiconductor devices at Infineon Technologies in Munich
Preparing: Logistics and paperwork for the internship
My internship was a little different from the other graduate fellows in my co-hort because it was in the fall quarter instead of the summer. This was planned due to strategic reasons for my PhD – I had some experiments I needed to finish during the summer months. Thus, I actually had more time to prepare for the upcoming internship, yet also had a few more hoops to jump. One major hoop was due to my fall enrollment status as a student away from Stanford. Summer quarter is quite forgiving – one does not need to be enrolled in classes to keep their on-campus housing and Cardinal Care health insurance. In order to keep these in the fall, I would have had to be actively enrolled (and thus paying tuition) even though I would be living abroad. Thus, I took one of my allowed “leave of absence” quarters and took a vacation quarter with housing. Also, I had to find my own health insurance for the quarter. I therefore agree with the program’s new decision to keep the internships only for the summer quarter due to this complicated restriction in the Stanford system.
Another unique challenge was having a paid internship for only 90 days. Thus, I had some exciting moments navigating the paperwork – most paid internships are much longer. I did not require a work visa, but needed a work permit (which they did check at customs!). With the help of the HR department, I was finally able to get answers to most of my questions. Looking back, many of these things were able to be resolved after arriving, but I appreciated knowing as much as possible before going. I can summarize what I learned here:
- Paid internships get taxed. The lowest tax bracket is granted to students who have registered their address OR have filled out a tax waiver form with their employer ID – valid for interns. I did the latter. If this was not filled out, I would have been charged the highest tax bracket.
- The voluntary internships require valid health insurance while in Germany. My company would have been able to enroll me in the public provider, but I had enrolled in my own “Health Care Abroad” insurance, which was also valid after all. Cardinal Care could have worked if this was a summer internship. (longer than 3 months is a different story). Looking back, I wish I had enrolled in the public system because there were many more options for appointments under the public system (at a glance). No one could tell me how much private insurance would cost out of pocket. Luckily, I did not need any appointments after all. I was nervous about enrolling before arriving, but this was not possible so I took a plan in the US that covered health care abroad.
- I was given access to a discounted monthly pass for public transportation in Germany – which I acquired during the first week at the central station. Public transportation was incredibly useful! I was able to get a “Green Youth Card” with extended my commuter pass to the whole of Munich at another affordable price.
- Short internships do not require registration (Anmeldung). But German bank accounts usually do. I got around this by making an N26 account, which does not require anmeldung if you verify identity with video conference with the proper documents. This was incredibly useful.
- Lots of documents got mailed to my apartment, so I was glad I took a place that I was able to receive mail. (My original Airbnb said I would not be able to receive mail there because it would get forwarded to another place). In general, Airbnb seems like a risky option regarding finding housing, so I ended up using another site called “Homelike.com” to find the pricey place close by.
Of course, there were some benefits for going in the fall – I was able to see the best of Munich during Oktoberfest and the Christmas market season. The paid internship also made it affordable to live in Munich, which usually has a very challenging housing market with tough prices.
Living in Munich
I chose to live outside of Munich, close to my company to make commuting easier and affordable. I found this to be a peaceful experience, but I did feel isolated from the city at times. I was able to go into town frequently with my public transportation passes. There is quite a bit to do in Munich! There are many museums that are only 1 Euro on Sundays, parks to explore, and the mountains not far away. A few highlights from my weekend adventures: I visited Dachau concentration camp, Andech’s Monastery & brewery, Oktoberfest, Neuschwanstein (The Castle that inspired Walt Disney), Nymphenberg Palace, and frequent trips to Christmas Markets. I also took some trips to other Bavarian towns like Freising, Regensberg, Nuremberg, and Mittenwald. The train system made these adventures possible – there are discount regional tickets (The Bayern Ticket) which allow unlimited day trips for only about 30 Euro – and it gets cheaper as a group ticket.
A major concern I had moving to Munich was how to find a social life, but I succeeded. I have very elementary German, but I tend to be a very social student at Stanford. I used my previous network to make connections in Munich and I also looked for social groups on social media. I also found the student buddy from TUM to be a nice point of contact and we had a few nice social meet ups. I also made friends at work. I was surprised by a few culture differences. Americans are very outgoing compared to our German peers at first, but Germans are warm, loyal, consistent friends once I was able to earn their trust. At work, lunch was always at the same time every day, and everyone would stay until everyone had finished their meal. We also frequently got coffee together right after lunch. This consistent social hour was refreshing every day – and it allowed us to get our tasks accomplished at work without distractions in our open-office layout. I found this culture and my new friendships to be a great experience during my time in Germany.
Munich is a large hub for travel through Europe, which I took advantage of during my time in Munich. I visited 8 cities outside of Bavaria both in Germany and abroad: Berlin, Ljubjana, Salzberg, Villach, London, Kraków, Warsaw, and Mainz. I was able to explore both on my own and meet up with previous family friends and acquaintances. Most of my trips were done through bahn.de, but I also took some affordable flights.
I found my internship at Infineon Technologies AG through my connections in my PhD lab. One of my PhD projects has sponsorship from the Automotive sensing group in Austria, and they got me in touch with my future mentor at the Innovative sensing group in Munich. I also made contact through a coterm student in my lab group who had previously worked in the same group. We had a skype interview and a few days later I got the offer. My mentor, David Tumpold, organized the internship so I would get to explore multiple topics across two groups. My first 6 weeks were spent in the Industrial Power Control division, and the last 7 weeks spent back in David’s group working on innovative sensing products.
Since my PhD is focused on the study of widebandgap semiconductors in extreme environments, I was happy to have a chance to work with Silicon Carbide (SiC) in its main industrial application as a power transistor. Infineon is leading the world in SiC MOSFET technology. During this part of the internship, I learned 6 new characterization techniques related to the testing of these devices for developing technical datasheets for the final products. In addition, I took on the ambitious task of pushing for the characterizations of a new SiC MOSFET product required for their first simulation models. I also determined a leading hypothesis for the suspicious behavior of some half-bridge switching prototypes.
My PhD in particular focuses on sensors made from widebandgap semiconductors, so the second half of my internship expanded my work in sensing. In this group, I was focused in much more “preliminary” work. This team develops concepts for new sensors. In fact, the microphones using in almost every smartphone was originally developed in this group. More recently, they have been exploring gas sensors of many different strategies. My task was to create a small-volume test apparatus to measure the effect of temperature fluctuations on the pressure environment to understand packaging influences. (In microphones are incredibly sensitivie to acoustic noise from the packaging environment). While this was not directly related to the gas sensor, this new hardward platform enables new experiments in the group and answered some vital questions for future modeling. In addition, I was also tasked with the evaluation of a complex gas spectrum model developed in house against the open-source version available online at hitran.org.
I returned from this internship with the following fruits. I know dynamic switching phenomenon in power electronics and intuition regarding the device behavior. I also learned quickly a new sensing mechanism and contribute to advanced modeling. Finally, I was able to drive challenging projects with a short timeline by leveraging my colleague’s expertise. These acquired skills and realizations empower me to pursue more opportunities on completion of my PhD.
This internship allowed me to grow professionally, technically, socially and personally. I learned a lot about myself. I learned how to adapt to a new culture and lifestyle. I also learned for the first time what it is like to live in a completely new place with few connections. I suppose this is something many young adults go through when they finish school, but it was extra challenging being in a new country with a different language. I hope to be aware of my peers at Stanford coming from far away and the similar challenges they may face here. However, I think back fond of my time in Munich, and hope to keep my new network of colleagues and friends close in the future. After my PhD, I hope to apply to post doc positions in similar topics, and include Infineon in my application pile. I also hope I can keep my German language learning alive while also finishing up my graduate school career. I also hope to return to Munich soon to see my new friends and colleagues and to finish exploring Europe! Finally, I want to recommend future students from my department to work in the same groups, they want more Stanford students!
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