다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

The field of visible light communications (VLC) has gained significant interest over the last decade, in both fibre and free-space embodiments. In fibre systems, the availability of low cost plastic optical fibre (POF) that is compatible with visible data communications has been a key enabler. In free-space applications, the availability of hundreds of THz of the unregulated spectrum makes VLC attractive for wireless communications. This paper provides an overview of the recent developments in VLC systems based on gallium nitride (GaN) light-emitting diodes (LEDs), covering aspects from sources to systems. The state-of-the-art technology enabling bandwidth of GaN LEDs in the range of >400 MHz is explored. Furthermore, advances in key technologies, including advanced modulation, equalisation, and multiplexing that have enabled free-space VLC data rates beyond 10 Gb/s are also outlined.

/pdf/a-review-of-gallium-nitride-leds-for-multi-gigabit-per-4fgs6zvkvk.pdf

A review of gallium nitride LEDs for multi-gigabit-per-second visible light data communications

Doping problems in GaN and in AlGaN alloys are addressed on the basis of state-of-the-art first-principles calculations. For n-type doping we find that nitrogen vacancies are too high in energy to be incorporated during growth, but silicon and oxygen readily form donors. The properties of oxygen, including DX-center formation, support it as the main cause of unintentional n-type conductivity. For p-type doping we find that the solubility of Mg is the main factor limiting the hole concentration in GaN. We discuss the beneficial effects of hydrogen during acceptor doping. Compensation of acceptors by nitrogen vacancies may occur, becoming increasingly severe as x increases in Al_x Ga_(1-x)N alloys.

https://arxiv.org/pdf/cond-mat/9810385.pdf

Theory of Doping and Defects in III-V Nitrides

Synthesis of Ce-doped SnO 2 nanoparticles and their acetone gas sensing properties

Metal organic vapour phase epitaxy of AlN, GaN, InN and their alloys: a key chemical technology for advanced device applications

The authors have studied the growth of bulk, freestanding zinc-blende (cubic) GaN layers by plasma-assisted molecular beam epitaxy (PA-MBE). They have established that the best structural properties of freestanding zinc-blende GaN can be achieved with initiation under Ga-rich conditions but without Ga droplet formation. It is difficult to initiate the growth of zinc-blende GaN, but it is even more difficult to sustain the growth of the pure zinc-blende polytype in thick layers without any wurtzite inclusions. In order to grow high quality freestanding cubic GaN layers, it is necessary to maintain the same growth conditions for about 1week. The best quality zinc-blende phase GaN was achieved in the first 10μm of the GaN layers. The authors have produced zinc-blende GaN substrates from our thick bulk GaN layers and they used the side previously attached to the GaAs substrate as the episide of these zinc-blende GaN substrates. They have demonstrated the scalability of the process by growing zinc-blende GaN l...

Molecular beam epitaxy as a method for the growth of freestanding zinc-blende (cubic) GaN layers and substrates

Alteration of structural and optical properties in quaternary Al0.1In0.1Ga0.8N films using ultraviolet assisted photo-electrochemical etching route

Measurements of the current-voltage characteristics of zinc-blende (cubic) Al0.3Ga0.7N/GaN, double barrier resonant tunneling diodes are presented. Clear and reproducible negative differential resistance effects are observed, with room temperature peak-to-valley ratios up to 4 and peak currents up to about 1000 A cm−2.

Current-voltage characteristics of zinc-blende (cubic) Al0.3Ga0.7N/GaN double barrier resonant tunneling diodes

Molecular beam epitaxy of crystalline and amorphous GaN layers with high As content

Using the technique of picosecond acoustics, we measure the basic elastic and optical properties of a micrometre-thickness zinc-blende (cubic) GaN epitaxial film grown on GaAs. We provide low temperature values of the speed of sound, c11 elastic constant and refractive index. Our value of the elastic constant is in good agreement with the theoretical calculations for cubic GaN (Wright 1997 J. Appl. Phys. 82 2833).

http://iopscience.iop.org/article/10.1088/0022-3727/42/11/115412/pdf

Norzaini Zainal

Papers

Molecular beam epitaxy as a method for the growth of freestanding zinc-blende (cubic) GaN layers and substrates

Alteration of structural and optical properties in quaternary Al0.1In0.1Ga0.8N films using ultraviolet assisted photo-electrochemical etching route

Current-voltage characteristics of zinc-blende (cubic) Al0.3Ga0.7N/GaN double barrier resonant tunneling diodes

Molecular beam epitaxy of crystalline and amorphous GaN layers with high As content

Elasto-optical properties of zinc-blende (cubic) GaN measured by picosecond acoustics