GaN-based semiconductor devices and materials

A new metallization scheme has been developed for obtaining very low Ohmic contact to n-GaN. The metallization technique involves the deposition of a composite metal layer Ti/Al/Ni/Au (150 Å/2200 Å/400 Å/500 Å) on n-GaN preceded by a reactive ion etching (RIE) process which most likely renders the surface highly n typ…

High quality indium tin oxide (ITO) thin films were grown without oxygen by both dc and RF magnetron sputtering techniques on glass substrates. The effects of substrate temperature, film thickness and sputtering method on the structural, electrical and optical properties of the as-grown films were investigated. The re…

• LÜTFİ ÖZYÜZER

High quality indium tin oxide (ITO) thin films were grown without oxygen by both dc and RF magnetron sputtering techniques on glass substrates. The effects of substrate temperature, film thickness and sputtering method on the structural, electrical and optical properties of the as-grown films were investigated. The re…

• GÜLNUR AYGÜN ÖZYÜZER

Three-dimensional (3D) GaN is a III-V compound semiconductor with potential optoelectronic applications. In this paper, starting from 3D GaN in wurtzite and zinc-blende structures, we investigated the mechanical, electronic, and optical properties of the 2D single-layer honeycomb structure of GaN ($g\ensuremath{-}\mat…

• ENGİN DURGUN

Motivated by a recent experiment that reported the successful synthesis of hexagonal $(h)$ AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013)], we investigate structural, electronic, and vibrational properties of bulk, bilayer, and monolayer structures of $h$-AlN by using first-principles calculations. We show t…

• ŞEYDA HORZUM ŞAHİN

Motivated by a recent experiment that reported the successful synthesis of hexagonal $(h)$ AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013)], we investigate structural, electronic, and vibrational properties of bulk, bilayer, and monolayer structures of $h$-AlN by using first-principles calculations. We show t…

• HASAN ŞAHİN

In this letter, we experimentally demonstrate direct correlation between efficiency droop and carrier overflow in InGaN/GaN green light emitting diodes (LEDs). Further, we demonstrate flat external quantum efficiency curve up to 400 A/cm2 in a plasma assisted molecular beam epitaxy grown N-polar double quantum well LE…

• FATİH AKYOL

We report a photometric study of ultra-efficient light emitting diodes (LEDs) that exhibit superior color rendering index (CRI) and luminous efficacy of optical radiation (LER) using semiconductor quantum dot nanocrystal (NC) luminophores. Over 200 million systematically varied NC-LED designs have been simulated to un…

• SEDAT NİZAMOĞLU

We report on the design and demonstration of polarization-engineered GaN/InGaN/GaN tunnel junction diodes with high current density and low tunneling turn-on voltage. Wentzel–Kramers–Brillouin calculations were used to model and design tunnel junctions with narrow band gap InGaN-based barrier layers. N-polar p-GaN/In0…

• FATİH AKYOL

The authors report on the use of hollow cathode plasma for low-temperature plasma-assisted atomic layer deposition (PA-ALD) of crystalline AlN, GaN and Al x Ga 1−x N thin films with low impurity concentrations.

• EDA GOLDENBERG

High quality n-ZnO films on commercial p-type 6H–SiC substrates have been grown by plasma-assisted molecular-beam epitaxy, and n-ZnO∕p-SiC heterojunction mesa structures have been fabricated. Current-voltage characteristics of the structures had a very good rectifying diode-like behavior with a leakage current less th…

• SEYDİ DOĞAN

The polar nature of the wurtzite crystalline structure of GaN and ZnO results in the existence of a spontaneous electric polarization within these materials and their associated alloys (Ga,Al,In)N and (Zn,Mg,Cd)O. The polarity has also important consequences on the stability of the different crystallographic surfaces,…

• FATİH AKYOL