نتایج جستجو برای: GaN
تعداد نتایج: 13601 فیلتر نتایج به سال:
Internal polarizations field which take place in quantum structures of group-III nitrides have an important consequence on their optical properties. Optical properties of wurtzite AlGaN/GaN quantum well (QW) structures grown by MBE and MOCVD on c-plane sapphire substrates have been investigated by means of photoluminescence (PL) and time resolved photoluminescence (TRPL) at low-temperature. PL ...
Nowadays, the semiconductor nanowires (NWs) typically used in hydrogen gas sensors. Gallium nitride (GaN) with a wide band gap of 3.4 eV, is one of the best semiconductors for this function. NWs surface roughness have important role in gas sensors performance. In this research, GaN NWs have been synthesized on Si substrate by plasma-assisted vapor phase deposition at different deposition time, ...
در این پایان نامه، دو مدل برای محاسبه ی ظرفیت کوانتومی در نانو ساختارهای نیتریدی ارائه شده است. اولین مدل بر پایه ی استفاده از چگالی حالات برای محاسبه ی ظرفیت کوانتومی در ساختار نیتریدی متشکل از ابرشبکه gan/aln و لایه نقاط کوانتومی inn می باشد. که وجود نقاط کوانتومی خود را به صورت یک پیک در نمودارهای ولتاژ- ظرفیت نشان می-دهد. اثرات دما، تعداد نقاط کوانتومی، تراز انرژی محبوس شده در نقاط کوانتومی...
AB Initio Study of Molecular Struture, Energetic and Vibrational Spectra of (GaN)4 Nanosemiconductor
In recent years there has been considerable interest in the structures, energies and thermodynamics of(GaN)4 clusters and it is the subject of many experimental and theoretical studies because of theirfundamental importance in chemical and physical process. All calculation of this study is carried outby Gaussian 98. Geometry optimization for (GaN)4 nanocluster are be fulfilled at B3LYP, B1LYPan...
in this work we use density functional theory based on the ultra-soft pseudo-potential to calculate thestructural, mechanical and thermal properties of narrow single walled bn, aln and gan nanotubes.the electron-electron interactions were expressed within the local density approximation (lda). wehave also obtained the phonon dispersion and elastic constants of these nanotubes using the densityf...
Thick GaN films, with (1120) or (1126) planes parallel to the r-plane of sapphire, were grown by molecular beam epitaxy using AlN or GaN buffer layers. Characterization by transmission electron microscopy revealed a high density of basal-plane stacking faults (BSFs) in the (1120) non-polar GaN (a-GaN) films. {1120} and {1010} prismatic-plane and {1102} pyramidal-plane stacking faults (SFs) doma...
This work reports both experimental and theoretical studies on the InGaN/GaN light-emitting diodes (LEDs) with optical output power and external quantum efficiency (EQE) levels substantially enhanced by incorporating p-GaN/n-GaN/p-GaN/n-GaN/p-GaN (PNPNP-GaN) current spreading layers in p-GaN. Each thin n-GaN layer sandwiched in the PNPNP-GaN structure is completely depleted due to the built-in ...
Gallium nitride (GaN) nanostructures (NS) were synthesized using pulseddirect current plasma enhanced chemical vapor deposition (PDC-PECVD) on quartzsubstrate at low temperature (600°C). Gallium metal (Ga) and nitrogen (N) plasma wereused as precursors. The morphology and structure of the grown GaN NS werecharacterized by field emission scanning electron microscope (FE-SEM), transmissionelectro...
N-GaN/P-GaN/N-GaN/P-GaN/N-GaN (NPNPN-GaN) junctions embedded between the n-GaN region and multiple quantum wells (MQWs) are systematically studied both experimentally and theoretically to increase the performance of InGaN/GaN light emitting diodes (LEDs) in this work. In the proposed architecture, each thin P-GaN layer sandwiched in the NPNPN-GaN structure is completely depleted due to the buil...
در این مقاله اثر پهنای سد و پهنای چاه کوانتومی gan/algan بر روی انرژی گذارهای اپتیکی و طیف فتولومینسانس آنها با استفاده از تکنیک فتولومینسانس مورد بررسی قرار گرفته است. مطالعه طیف فتولومینسانس این چاه های کوانتومی در دماهای پایین نشان می دهد که نحوه تغییرات انرژی گذار اپتیکی بر حسب پهنای سد در ساختارهای کوانتومی gan/algan بر خلاف آنچه که در سایر نیمرساناها از قبیل آلیاژهای gaas مشاهده شده, می ب...
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