The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
2016 Compound Semiconductor Week (CSW) [Includes 28th International Conference on Indium Phosphide & Related Materials (IPRM) & 43rd International Symposium on Compound Semiconductors (ISCS)
An E-mode GaN MIS-HEMTs using multilayer La2O3/HfO2 as gate insulator is investigated for high power application. The multilayer La2O3/HfO2 composite oxide transformed to HfLaOx amorphous phase with low density of interface traps and border traps after post deposition annealing (PDA) at 6000C as judged from the C-V characteristics of the HfLaOx/GaN MOSCAP. The device exhibits a low ON-resistance of...
The GaN HEMT power device with field plate for device reliability improvement is investigated. Overall, the field plate structure smooths the electrical field distribution in the HEMT structure and reduces the generation of defects and the interface traps in the device, resulting in higher device breakdown voltage, lower leakage current, and less current degradation with steady dynamic on-resistance...
In situ synchrotron X-ray diffraction studies during the growth of arsenide and nitride semiconductors are presented. The large penetration depth of X-rays was exploited for revealing structural changes at buried interfaces as well as near the surface. Experiments were performed at a synchrotron beamline, BL11XU, SPring-8, using a molecular-beam epitaxy chamber integrated with a high-precision X-ray...
III-nitride semiconductor based heterojunction field effect transistors (HFETs) with metal insulator semiconductor (MIS) structure have attracted much attention as power semiconductor devices that enable low-loss and high-power driving. Amorphous alumina (Al2O3) was deposited by atomic layer deposition (ALD), which has appropriate physical properties as gate dielectric in MIS-HFETs, such as high relative...
The band alignments between Atomic-Layer-Deposited (ALD) high-k ZrO2 and wide bandgap semiconductors: GaN, AlN and SiC were investigated using X-ray photoelectron spectroscopy (XPS). Based on angle-resolved XPS measurements combined with numerical calculations, the conductor and valence band discontinuities at the interface between ZrO2 and wide bandgap semiconductors were determined by taking surface...
Eu doped GaN (GaN:Eu) shows a sharp line emission and thermal stability of the emission wavelength. To improve the optical properties, GaN:Eu nanocolumns were grown on GaN nanocolumn platform with high crystalline quality by rf-plasma-assisted molecular beam epitaxy. Although it was revealed that an increase of Eu concentration brought about the polycrystalline growth, photoluminescence (PL) intensity...
Excitation and deexcitation dynamics of excitons and biexcitons are calculated on the basis of the collisions of excitons, electrons, and phonons. Fröhlich, deformation, and piezo-electric interactions are taken into account for the phonon collision system. A set of rate equations on populations of exciton states of several principal quantum numbers (p), free electrons, biexciton states of hydrogen...
We investigate the bow of free standing (0001) oriented HVPE grown GaN wafers and demonstrate that their curvature is consistent with a compressive to tensile stress gradient (bottom to top) present in the wafers. The origin of the stress gradient and the curvature is attributed to the inclination of edge threading dislocations (TDs) with respect to original [0001] GaN wafer or boule growth direction...
InGaN/GaN multiple quantum well (MQW) nano-scale light emitting diodes (nano-LEDs) were fabricated by a hydrogen environment anisotropic thermal etching (HEATE) technique. HEATE is a GaN selective etching technique using SiO2 masks based on thermal decomposition reaction of GaN in hydrogen environment at high-temperature around 800 1100°C. An InGaN/GaN MQW blue LED epitaxial wafer grown on (0001)...
Low-temperature data of Hall-effect measurements on n- and p-type GaN reported in literature, which exhibit the characteristic of nearest-neighbor hoping (NNH) conduction in an impurity band, are analyzed with taking into account the temperature dependence of the Hall factor for NNH conduction. It is found that, for both samples of n- and p-type GaN, the Hall factor for NNH conduction are negative,...
In this study, we have grown cubic InN (c-InN) nano-scale dot arrays using MgO (001) vicinal substrates (3.5 deg. off from (001) toward [110]) by molecular beam epitaxy. The obtained dot arrays have longer ordering length (>1 um) compared with those grown on MgO (001) just substrates. By using MgO (001) vicinal substrates, the structure of cubic GaN (c-GaN) underlayer changed from a mixture of...
Carbon is a readily incorporated impurity during growth in GaN and is known for deteriorating the electronic properties of devices. We study the diffusion of carbon in GaN employing Density Functional Theory. We compute the migration barriers of carbon interstitials and we propose possible mechanisms of diffusion in the wurtzite GaN crystal. The Minimum Energy Paths (MEP) and the migration barriers...
We report a novel thin-film flip-chip (TF-FC) c-plane GaN LED design grown on bulk GaN. By way of a photoelectrochemical (PEC) undercut etch, LEDs are transferred from a bulk GaN substrate to a sapphire submount. As a first demonstration, the resulting LEDs have threshold voltages below 3V and a peak external quantum efficiency (EQE) of 8.4% at a wavelength of 471 nm. These results are of LEDs without...
This paper presents the origin of gallium (Ga) incorporation into AlN layers grown by metalorganic vapor phase epitaxy (MOVPE). We systematically investigated Ga incorporation from GaN deposits on the inner walls of a growth reactor and an underlying GaN layer. The Ga incorporation is not affected by the GaN deposits on the inner walls of the reactor, but is strongly affected by the underlying GaN...
We report a novel, reliable, and scalable technique for the surface nanostructuring of GaN by colloidal lithography. Moth-eye protuberances of varying dimensions have been formed on bulk GaN substrates and on samples containing an InGaN multiple-quantum-well active layer, grown by metal organic chemical vapor deposition. Angle-resolved optical characterization and photoluminescence (PL) indicates...
Acidic ammonothermal method is one of the most promising techniques which enable the mass production of large diameter bulk GaN crystal. State-of-the-art high-power light-emitting diodes and laser diodes are usually fabricated on GaN substrates grown by hydride vapor phase epitaxy. However, to realize vertically conducting high-power GaN switching devices, bowing-free large-diameter GaN substrates...
The control and assessment of doping in GaN nanostructures are crucial for the realization of GaN based nanodevices. In this study, we have investigated a series of Si-doped GaN nanowires (NWs) grown by molecular beam epitaxy (MBE) with a typical dimension of 2–3 µm in length, and 20–200 nm in radius. In particular, high resolution energy dispersive X-ray spectroscopy (EDX) has illustrated a higher...
GaN-based nanowires (NWs) are attracting interest for realizing highly luminant light emitters, which fill green gaps of current LEDs, and selective-area growth (SAG) is one of the key technologies for their realization. We investigated the influences of mask materials in SAG of GaN using RF-molecular beam epitaxy (RF-MBE), and found significant differences of the growth conditions and growth modes...
We have investigated the geometric and electronic structures of thin films and atomic layers of GaN on the basis of density functional theory. We found that a monolayer GaN prefers a planar structure as its stable conformation with indirect band gap of 2.28 eV. We also showed the possible structure of hydrogenated GaN that possesses a buckled structure with a direct energy gap. Hydrogen concentration...
GaN-on-Si power devices are highly desirable for energy-efficient and compact power conversion systems. However, their performance and stability/reliability can be adversely affected by dynamic charging/discharging of interface and bulk traps. These issues need to be addressed by developing new processing technologies or structure designs, while appropriate characterization techniques are essential...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.