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Advances in GaN Crystals and Their Applications
摘要： This special issue looks at the potential applications of GaN-based crystals in both ?elds of nano-electronics and optoelectronics. The contents will focus on the fabrication and characterization of GaN-based thin ?lms and nanostructures. It consists of six papers, indicating the current developments in GaN-related technology for high-ef?ciency sustainable electronic and optoelectronic devices, which include the role of the AlN layer in high-quality AlGaN/GaN heterostructures for advanced high-mobility electronic applications and simulation of GaN-based nanorod high-ef?ciency light-emitting diodes for optoelectronic applications. From the results, one can learn the information and experience available in the advanced fabrication of nanostructured GaN-based crystals for nano-electronic and optoelectronic devices.
关键词： MOSFET,AlN,InN,InGaN,AlGaN,LED,GaN
更新于2025-09-23 15:21:21
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Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy
摘要： We directly measure the electric dipole of inn quantum dots (QDs) grown on in-rich inGan layers by Kelvin probe force microscopy. This significantly advances the understanding of the superior catalytic performance of inn/inGan QDs in ion- and biosensing and in photoelectrochemical hydrogen generation by water splitting and the understanding of the important third-generation inGan semiconductor surface in general. the positive surface photovoltage (SpV) gives an outward QD dipole with dipole potential of the order of 150 mV, in agreement with previous calculations. After HCl-etching, to complement the determination of the electric dipole, a giant negative SpV of ?2.4 V, significantly larger than the inGan bandgap energy, is discovered. this giant SpV is assigned to a large inward electric dipole, associated with the appearance of holes, matching the original QD lateral size and density. Such surprising result points towards unique photovoltaic effects and photosensitivity.
关键词： electric dipole,Kelvin probe force microscopy,surface photovoltage,inn/inGan quantum dots,photovoltaic effects
更新于2025-09-23 15:21:01
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Reference Module in Materials Science and Materials Engineering || Organometallic Vapor Phase Epitaxial Growth of Group III Nitrides ☆
摘要： The III-nitrides of aluminum nitride (AlN), gallium nitride (GaN), and indium nitride (InN) and their solid solutions form most commonly in the low-temperature wurtzite crystal structure shown in Fig. 1(a). Overall, this structure possesses a hexagonal unit cell with lattice constants c (o00014 axes) and a (o11204 axes). The atomic arrangement within this structure consists of two interpenetrating, closest packed metal and nitrogen lattices in which each atom of one type is bonded to four atoms of the other to form AB4 tetrahedra. The space group is P63mc.
关键词： GaN,OMVPE,Organometallic Vapor Phase Epitaxy,Group III Nitrides,Polarization,Dislocations,InN,Buffer Layers,AlN,Substrates
更新于2025-09-23 15:21:01
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Metallic indium segregation control of InN thin films grown on Si(1?0?0) by plasma-enhanced atomic layer deposition
摘要： InN thin films were grown on Si(1 0 0) substrates by plasma-enhanced atomic layer deposition (PEALD). In this work, It is found that the island growth of InN on Si(1 0 0) easily happens at the initial PEALD period. The PEALD parameters have been systematically investigated to optimize the size, density, coalescence and distribution uniformity of InN grains with good crystallinity and no metallic indium clustering. Especially, indium segregation of PEALD-grown InN has a direct dependence on the deposition temperature (T), the supply of tri-methylindium (TMIn) precursor and nitrogen plasma (NP) source. Based on our proposed PEALD mechanism of InN, a polycrystalline hexagonal InN thin film in the thickness of 24.2 nm has been well deposited at the growth per cycle (GPC) of 0.8 ?/cycle. And it shows a (0 0 2) preferential orientation and no any structural phase of metallic indium segregation. As a result, it may provide a useful guide for deeply understanding the PEALD growth mechanism of InN and In-rich nitrides, which further extends the promising applications in high-efficiency photovoltaics and high speed electronic devices.
关键词： Indium segregation,PEALD,Growth mechanism,InN,Polycrystalline
更新于2025-09-23 15:19:57
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Calculations of defect states in various sizes of InN nanowires
摘要： InN has received considerable attentions due to its small band-gap and unique properties in the III-nitride family. Understanding the effects of defects on optoelectronic properties of InN nanowire is essential for exploring its applications in future nanodevices. In this work, we have systematically calculated defect states in InN nanowires based on density-functional theory. Hydrogen passivation and several potential intrinsic point defects are considered in various sizes of nanowires, as well as charged defect states. For small-sized hexagonal nanowires, VN at N-poor condition or NIn at N-rich condition is the most stable defect. Whereas for larger-sized nanowires, VN and InN defects are competing when the N chemical potential changes, showing obvious size effect of the defect stability on the nanowire surface. Those defect states change the electronic structure of the nanowires drastically by introducing empty bands or deep level and provide possibility to tailor the optical properties in terms of forming different stable defects.
关键词： InN,nanowires,size effect,first-principals calculations,electronic structure,defects
更新于2025-09-19 17:15:36
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Growth Mechanism and Properties of Self-Assembled InN Nanocolumns on Al Covered Si(111) Substrates by PA-MBE
摘要： Self-assembled InN nanocolumns were grown at low temperatures by plasma-assisted molecular beam epitaxy with a high crystalline quality. The self-assembling procedure was carried out on AlN/Al layers on Si(111) substrates avoiding the masking process. The Al interlayer on the Si(111) substrate prevented the formation of amorphous SiN. We found that the growth mechanism at 400 ?C of InN nanocolumns started by a layer-layer (2D) nucleation, followed by the growth of 3D islands. This growth mechanism promoted the nanocolumn formation without strain. The nanocolumnar growth proceeded with cylindrical and conical shapes with heights between 250 and 380 nm. Detailed high-resolution transmission electron microscopy analysis showed that the InN nanocolumns have a hexagonal crystalline structure, free of dislocation and other defects. The analysis of the phonon modes also allowed us to identify the hexagonal structure of the nanocolumns. In addition, the photoluminescence spectrum showed an energy transition of 0.72 eV at 20 K for the InN nanocolumns, con?rmed by photore?ectance spectroscopy.
关键词： InN nanocolumns,Al interlayer,molecular beam epitaxy,self-assembly of nanocolumns
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Novel InN-Based SESAMs with Ultra-Short Time Response
摘要： Semiconductor saturable absorbers are becoming a matter of interest since they are keystone elements of pulsed lasers, leading to ultrashort pulses with high peak intensities and wide optical spectra. This kind of ultrafast lasers are empowering new applications in the fields of optical telecommunications and nonlinear optics. In order to improve the radiation source with regard to pulse energy and temporal duration, new saturable absorbers are still under development. In this work, we study semiconductor saturable absorbers (S1 and S2) consisting of an active InN layer grown by molecular beam epitaxy directly on a 10-μm-thick GaN-on-sapphire template. We compare structures with an InN thickness of 400 nm (S1) and 900 nm (S2). The energy band gap of the samples extracted from optical transmission measurements is Eg1 ～ 0.69 eV (1782 nm) and Eg2 ～ 0.70 eV (1767 nm) for samples S1 and S2, respectively. The nonlinear absorption of the samples at 1550 nm has been measured by the Z-scan method, using a radiation source which delivers 250 fs pulses with an average power of 35 mW and a repetition rate of 5.2 MHz. To increase the power density impinging the sample, the laser is focused with a lens with a focal length of 3 cm in the Z-scan scheme, attaining an energy fluence of E = 5.2 mJ/cm2. The nonlinear optical response of the samples is obtained by measuring the optical transmittance as a function of the incident peak intensity on the sample. In both samples, a huge nonlinear change is observed. The linear transmittance at 1550 nm has been estimated in Tlin = 17 % for S1 and Tlin = 2.6 % for S2, and the modulation depth is ΔT (S1) = 22.6 % and ΔT (S2) = 21.8 %, respectively. Thus, sample S1 exhibits a nonlinear transmittance change (Tnl/Tlin) above ～ 240% at the maximum peak intensity (optical bleaching), whereas for S2 the total change in transmittance reaches 815%. These results reveal that the thickness of S2 is particularly adapted for the fabrication of saturable absorbers at 1550 nm, since it is thick enough to get a low linear transmittance but keeping the maximum modulation depth. Semiconductor saturable mirrors (SESAMs) have been implemented by deposition of an aluminium mirror directly on the InN sample surface. Optical fiber mode-locked lasers have been developed with these SESAMs. The AC traces and optical spectra for lasers using samples S1 and S2 are plotted. The traces have been fitted to Gaussian curves with a temporal width of 210 fs for S1 and 150 fs for S2. In conclusion, we present a new SESAM technology based on InN thin films which displays huge nonlinear effects. Optimized InN layer thickness results in more than 800% change in transmittance, which makes it possible to generate ultrashort pulses with temporal duration as low as 150 fs.
关键词： Semiconductor saturable absorbers,InN,ultrafast lasers,SESAMs,nonlinear optics
更新于2025-09-12 10:27:22
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Indium Nitrite (InN)-Based Ultrasensitive and Selective Ammonia Sensor Using an External Silicone Oil Filter for Medical Application
摘要： Ammonia is an essential biomarker for noninvasive diagnosis of liver malfunction. Therefore, selective detection of ammonia is essential for medical application. Here, we demonstrate a portable device to selectively detect sub-ppm ammonia gas. The presented gas sensor is composed of a Pt coating on top of an ultrathin Indium nitrite (InN) epilayer with a lower detection limit of 0.2 ppm, at operating temperature of 200 ?C, and detection time of 1 min. The sensor connected with the external ?lter of nonpolar 500 CS silicone oil to diagnose liver malfunction. The absorption of 0.7 ppm acetone and 0.4 ppm ammonia gas in 10 cc silicone oil is 80% (0.56 ppm) and 21.11% (0.084 ppm), respectively, with a ?ow rate of 10 cc/min at 25?C. The absorption of acetone gas is 6.66-fold higher as compared to ammonia gas. The percentage variation in response for 0.7 ppm ammonia and 0.7 ppm acetone with and without silicone oil on InN sensor is 17.5% and 4%, and 22.5%, and 14% respectively. Furthermore, the percentage variation in response for 0.7 ppm ammonia gas with silicone oil on InN sensor is 4.3-fold higher than that of 0.7 ppm acetone. The results show that the InN sensor is suitable for diagnosis of liver malfunction.
关键词： silicone oil,InN,liver malfunction,exhaled-breath volatile organic compound (VOCs),selectivity,external ?lter
更新于2025-09-10 09:29:36
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Electrical Performances of InN/GaN Tunneling Field-Effect Transistor
摘要： In this paper, we design and analyze the InN/GaN double-gate (DG) tunneling ?eld-effect transistor (TFET) with very steep switching and superb DC and RF characteristics. The proposed device is closely investigated in terms of both DC and RF performances including Ioff, on/off current ratio (Ion/Ioff), subthreshold swing (S), cut-off frequency (ft), maximum oscillating frequency (fmax), and Johnson’s ?gure of merit (JFOM) using TCAD simulation. The proposed InN/GaN TFET shows high current drivability, extremely suppressed Ioff, and higly sharp switching owing to the effects by the electron well formed by the control gate (CG) in the InN layer. The InN/GaN TFET having a channel length (Lch) of 50 nm demonstrated maximum Ion = 3.5 mA/μm, extremely low Ioff = 1 × 10?21 A/μm, minimum S of 8.8 mV/dec, and the maximum values of ft and fmax are obtained as 100 GHz and 5.5 THz, respectively. In order to con?rm the high performances of the devices in the RF operation, JFOM has been calculated and the value extracted from an optimally designed InN/GaN TFET is 1.7 THz · V.
关键词： III-Nitride Heterojunction,Double Gate,Gallium Nitride,Power Device,InN/GaN,Field-Effect Transistor
更新于2025-09-04 15:30:14