Advanced Semiconductor Laboratory
Developing cutting-edge technologies based on III-nitride semiconductors

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Monthly Archives: February 2017

Hexagonal Boron Nitride, direct bandgap or indirect bandgap?

Feng Wu - February 27, 2017

Hexagonal Boron Nitride, direct bandgap or indirect bandgap?
Hexagonal boron nitride has attracted a lot of attentions because of its unique properties, such as a wide bandgap, low dielectric constant, high thermal conductivity, and chemical inertness. In spite of this rising interest in hBN and the large number of studies devoted to this material, with its seemingly simple crystal structure, the very basic question of the nature of its bandgap remains controversial, that is whether it is a direct bandgap or indirect bandgap.

III-Nitride Based High Electron Mobility Transistor

Wenzhe Guo - February 26, 2017

In 1956, three physicists were awarded the Nobel Prize for the discovery of transistor effect. Transistors have contributed to the development and improvement of integrated circuits and hence the extraordinary progress of information technology. Conventional transistors are realized based on the n-doped or p-doped Si material, which are limited in the high-frequency and high-power application. 

Playing guitar with photons: part 1: nonlinear optics conversion

Ronghui Lin - February 25, 2017

The conversion of photon frequency is an important function in quantum communication and quantum computation. Yet it is nontrivial because the frequency of a photon is related to the energy, thus to change the frequency of a photon, additional energy input is required. ​ 

π = 22/7

Nasir Alfaraj - February 25, 2017

High school students have often been misled to believe that 22/7 is either the actual value of π or an acceptable approximation to π. Here, I show that 355/113 is a better approximation of π in terms of both absolute and relative errors.​​​

My first month in KAUST

Crystal Hu - February 25, 2017

​I arrived at KAUST on Jan 16th and have been here for more than one month. During this month, it’s the peaceful environment in KAUST that touches my heart. The Red Sea is near our academic buildings. The fresh air, blue sky, warm sunshine, and the sound of water flow make up the campus. The culture here is very different with the culture in my country, China. But it is an interesting thing to experience a different life. I like to go swimming and play bowling after work. I am trying to study swimming now with my friends’ help. I am also not good at bowling, but after practicing many times, I do better now.

MOCVD growth regions

Kuang-Hui Li - February 23, 2017

There are three growth regions for MOCVD. They are kinetic limit, mass transport limit, and thermodynamic limit, as shown in Fig. 1. The kinetic limit happens at low temperature; the mass transport limit happens at medium temperature; the thermodynamic limit happens at high temperature.
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