Cree Interview Questions | Glassdoor

# Companies matching "Cree"

Cree Interviews

www.cree.com /  HQ: Durham, NC

199 Interviews

3.3 Difficult

CREECO Interviews

www.creeco.ca /  HQ: Oujé-Bougoumou

0 Interviews

Not Yet Rated

0 Interviews

Not Yet Rated

## Cree Interview Questions

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### Process Development Engineer at Cree was asked...

Oct 30, 2011
 Can Si be used to make LEDs ?3 AnswersSi can be used as a substrate in LEDs, but it cannot be used in the p-n junction because the bandgap energy is too small to produce visible light.Technically: Yes. But it has an indirect bandgap, so you really wouldn't want to.The energy bandgap of Si at room temperature is 1.12eV. Since the relationship between photon energy and wavelength is E(eV)=1.24/wavelength(micrometers), one can calculate that Si could emit a ligth in infrared optical spectrum: wavelength=1.24/1.12eV=1.11 micrometers. BUT, Si is indirect semiconductor! And therefore does not emit significant amounts of light due to the requirement of momentum conservation in optical transitions.

### Process Development Engineer at Cree was asked...

Mar 18, 2011
 How many barbers to cut men's hair in a city of 2 million people?2 Answers~3000 barbers. Work your way to the answer.I got the same answer, based on eight hour work days with 2 weeks of vacation each year. Based on the interviews I have read, if CREE hired the barbers, they would only need 1500, since they would be working 80-hour weeks.

### Process Engineer at Cree was asked...

Dec 4, 2013
 If an ice cube melts in water, does the water level rise or fall? Explain with details.3 AnswersNo, the water neither rises nor falls. The buoyancy of the ice does not affect the water level, it will raise the water level if you add ice to an already full glass of water, however because ice is lighter than the water (which is the oddity of water as an element versus other elements on the periodic table), the level stays the same.no, although the ice melts in a certain container if it is floating on a water the volume of ice is already condense on the water itself so water level will never changeno, the water level will remain the same because the displacement of the ice cube is what determines water level,not the volume of the portion of the ice cube that is submerged.

### Process Engineer at Cree was asked...

Dec 4, 2013
 If you're stuck in the middle of nowhere with a broken down car, how can you determine what the problem is?3 AnswersIt seems you have no gas.but when you encountered an engine trouble you cannot easily determine the problem without knowledge of it.objective: For example: diagnose & fix the car; or get out of nowhere; be at peace with being nowhere.Hmmmm, "If you're stuck in the middle of nowhere with a broken down car, how can you determine what the problem is?" A. The problem is obvious :0 You're stuck in the middle of nowhere and your car is broken down! Hopefully you have a cell phone with a cell tower nearby.

### Process Development Engineer at Cree was asked...

Feb 29, 2012
 If a glass of water is half full and you put ice in it, when ice melts, the water level will increase of decrease or remain constant? Give scientific reason.2 AnswersIt will remain constantThe ice will float with a fraction of the ice cube sticking above the surface which is determined by the ratio of the density of water to the density of ice. Since these densities do not change as the ice melts, the fraction of ice above the water surface will never change. Since the fraction of ice above the water's surface never changes, the volume decrease of ice below the water surface during melting is always exactly replaced with an equivalent volume of melt. Therefore the water level in the glass will not change throughout the melting process.

### Process Engineer at Cree was asked...

May 16, 2011
 Difference between turbo and cryo vacuum pump?2 AnswersA cryo pump uses a cryogenic fluid that entraps the gas molecules inside the chamber and freezes them below their freezing point. A cryo pump doesn't work very well with gases like He or H2. A turbo pump has a mechanical blade that is rotating at a very high speed and pulls the gases out of the system, imagine a jet engine on an airplane. The cryo pump is efficient if for ultra high vacuum ranges >10^-8 Torr compared to turbo. Both pumps require a small mechanical pump attached to the chamber to provide the lower level vacuum in the 10^-3 Torr range before they take over.A cryo pump uses a cryogenic fluid that entraps the gas molecules inside the chamber and freezes them below their freezing point. A cryo pump doesn't work very well with gases like He or H2. A turbo pump has a mechanical blade that is rotating at a very high speed and pulls the gases out of the system, imagine a jet engine on an airplane. The cryo pump is efficient if for ultra high vacuum ranges >10^-8 Torr compared to turbo. Both pumps require a small mechanical pump attached to the chamber to provide the lower level vacuum in the 10^-3 Torr range before they take over.

### Process Development Engineer at Cree was asked...

Mar 7, 2013
 Estimate the number of flat tyres in the US in a year?3 AnswersGive a ball park figure based on your reasoning. Should be simplePer Wiki, 220 million. One would need to know how many cars are driven in US or that a flat tire occurs every 7 seconds. Did you know "Current US Population is 314.69 million".345632. How can you say that? Go count yourself

### Design Negineer at Cree was asked...

Dec 29, 2009
 why you leave the current company1 Answerwant to relocate

### Design Negineer at Cree was asked...

Dec 29, 2009
 salary expectation1 Answerdifferent city and different living expenses, but don't expect to be lower than what I currently have

### Process Development Engineer at Cree was asked...

Mar 18, 2011
 Where would you use this kind of screw (from a bunch of screws)? [very interesting questions, i must say]1 AnswerSimple general knowledge questions. Some of them may be related to your job position!
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