Materials

Research

9 pages, 3301 KiB

Open AccessArticle

E-Band InAs Quantum Dot Micro-Disk Laser with Metamorphic InGaAs Layers Grown on GaAs/Si (001) Substrate

by Wenqian Liang, Wenqi Wei, Dong Han, Ming Ming, Jieyin Zhang, Zihao Wang, Xinding Zhang, Ting Wang and Jianjun Zhang

Materials 2024, 17(8), 1916; https://0-doi-org.brum.beds.ac.uk/10.3390/ma17081916 - 21 Apr 2024

Viewed by 430

Abstract

The direct growth of III-V quantum dot (QD) lasers on silicon substrate has been rapidly developing over the past decade and has been recognized as a promising method for achieving on-chip light sources in photonic integrated circuits (PICs). Up to date, O- and [...] Read more.

The direct growth of III-V quantum dot (QD) lasers on silicon substrate has been rapidly developing over the past decade and has been recognized as a promising method for achieving on-chip light sources in photonic integrated circuits (PICs). Up to date, O- and C/L-bands InAs QD lasers on Si have been extensively investigated, but as an extended telecommunication wavelength, the E-band QD lasers directly grown on Si substrates are not available yet. Here, we demonstrate the first E-band (1365 nm) InAs QD micro-disk lasers epitaxially grown on Si (001) substrates by using a III-V/IV hybrid dual-chamber molecular beam epitaxy (MBE) system. The micro-disk laser device on Si was characterized with an optical threshold power of 0.424 mW and quality factor (Q) of 1727.2 at 200 K. The results presented here indicate a path to on-chip silicon photonic telecom-transmitters. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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12 pages, 3673 KiB

Open AccessArticle

Growth of Ga_0.70In_0.30N/GaN Quantum-Wells on a ScAlMgO₄ (0001) Substrate with an Ex-Situ Sputtered-AlN Buffer Layer

by Dong-Guang Zheng, Sangjin Min, Jiwon Kim and Dong-Pyo Han

Materials 2024, 17(1), 167; https://0-doi-org.brum.beds.ac.uk/10.3390/ma17010167 - 28 Dec 2023

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Abstract

This study attempted to improve the internal quantum efficiency (IQE) of 580 nm emitting Ga_0.70In_0.30N/GaN quantum-wells (QWs) through the replacement of a conventional c-sapphire substrate and an in-situ low-temperature GaN (LT-GaN) buffer layer with the ScAlMgO₄ (0001) [...] Read more.

This study attempted to improve the internal quantum efficiency (IQE) of 580 nm emitting Ga_0.70In_0.30N/GaN quantum-wells (QWs) through the replacement of a conventional c-sapphire substrate and an in-situ low-temperature GaN (LT-GaN) buffer layer with the ScAlMgO₄ (0001) (SCAM) substrate and an ex-situ sputtered-AlN (sp-AlN) buffer layer, simultaneously. To this end, we initially tried to optimize the thickness of the sp-AlN buffer layer by investigating the properties/qualities of an undoped-GaN (u-GaN) template layer grown on the SCAM substrate with the sp-AlN buffer layer in terms of surface morphology, crystallographic orientation, and dislocation type/density. The experimental results showed that the crystallinity of the u-GaN layer grown on the SCAM substrate with the 30 nm thick sp-AlN buffer layer [GaN/sp-AlN(30 nm)/SCAM] was superior to that of the conventional u-GaN template layer grown on the c-sapphire substrate with an LT-GaN buffer layer (GaN/LT-GaN/FSS). Notably, the experimental results showed that the structural properties and crystallinity of GaN/sp-AlN(30 nm)/SCAM were considerably different from those of GaN/LT-GaN/FSS. Specifically, the edge-type dislocation density was approximately two orders of magnitude higher than the screw-/mixed-type dislocation density, i.e., the generation of screw-/mixed-type dislocation was suppressed through the replacement, unlike that of the GaN/LT-GaN/FSS. Next, to investigate the effect of replacement on the subsequent QW active layers, 580 nm emitting Ga_0.70In_0.30N/GaN QWs were grown on the u-GaN template layers. The IQEs of the samples were measured by means of temperature-dependent photoluminescence efficiency, and the results showed that the replacement improved the IQE at 300 K by approximately 1.8 times. We believe that the samples fabricated and described in the present study can provide a greater insight into future research directions for III-nitride light-emitting devices operating in yellow–red spectral regions. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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9 pages, 8749 KiB

Open AccessCommunication

Growth and Dark Current Analysis of GaSb- and InP-Based Metamorphic In_0.8Ga_0.2As Photodetectors

by Peng Cao, Tiancai Wang, Hongling Peng, Qiandong Zhuang and Wanhua Zheng

Materials 2023, 16(13), 4538; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16134538 - 23 Jun 2023

Cited by 2 | Viewed by 989

Abstract

Short-wavelength infrared photodetectors based on metamorphic InGaAs grown on GaSb substrates and InP substrates are demonstrated. The devices have a pBn structure that employs an AlGaAsSb thin layer as the electron barrier to suppress dark current density. The strain effect on the electrical [...] Read more.

Short-wavelength infrared photodetectors based on metamorphic InGaAs grown on GaSb substrates and InP substrates are demonstrated. The devices have a pBn structure that employs an AlGaAsSb thin layer as the electron barrier to suppress dark current density. The strain effect on the electrical performance of the devices was specifically studied through the growth of the pBn structure on different substrates, e.g., InP and GaSb, via a specific buffering technique to optimize material properties and minimize dark current. A lower device dark current density, down to 1 × 10⁻² A/cm² at room temperature (295 K), was achieved for the devices grown on the GaSb substrate compared to that of the devices on the InP substrate (8.6 × 10⁻² A/cm²). The improved properties of the high-In component InGaAs layer and the AlGaAsSb electron barrier give rise to the low dark current of the photodetector device. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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11 pages, 3033 KiB

Open AccessArticle

Optoelectronic Properties of In_0.87Ga_0.13As_0.25P_0.75(001)β₂(2×4) Surface: A First-Principles Study

by Yong Wang, Jianxin Li, Junju Zhang and Weiwei Sha

Materials 2023, 16(7), 2834; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16072834 - 2 Apr 2023

Viewed by 891

Abstract

InGaAsP photocathode surface affects the absorption, transport and escape of photons, and has a great influence on quantum efficiency. In order to study InGaAsP photocathode surface, the electronic structure, work function, formation energy, Mulliken population and optical properties of In_0.87Ga_0.13 [...] Read more.

InGaAsP photocathode surface affects the absorption, transport and escape of photons, and has a great influence on quantum efficiency. In order to study InGaAsP photocathode surface, the electronic structure, work function, formation energy, Mulliken population and optical properties of In_0.87Ga_0.13As_0.25P_0.75(001)β₂(2×4) reconstruction surface were calculated from first principles. Results show that stabilized the In_0.87Ga_0.13As_0.25P_0.75(001)β₂(2×4) surface is conducive to the escape of low-energy photoelectrons. The narrow bandgap and emerging energy levels of the reconstruction surface make the electron transition easier. Under the action of the dipole moment, the electrons transfer from inner layers to the surface during the surface formation process. By contrast to the bulk, the surface absorption coefficient and reflectivity considerably decrease, and the high-reflection range becomes narrower as the falling edge redshifts. On the contrary, the surface transmissivity increases, which is conducive for the photons passing through the surface into the bulk to excite more photoelectrons. Meanwhile, the higher absorption coefficient of surface in low-energy side is favorable for long-wave absorption. The dielectric function peaks of the surface move toward the low-energy side and peak values decrease. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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12 pages, 3398 KiB

Open AccessEditor’s ChoiceArticle

Selective-Area Growth Mechanism of GaN Microrods on a Plateau Patterned Substrate

by Min-joo Ahn, Woo-seop Jeong, Kyu-yeon Shim, Seongho Kang, Hwayoung Kim, Dae-sik Kim, Junggeun Jhin, Jaekyun Kim and Dongjin Byun

Materials 2023, 16(6), 2462; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16062462 - 20 Mar 2023

Cited by 1 | Viewed by 1694

Abstract

This study provides experimental evidence regarding the mechanism of gallium nitride (GaN) selective-area growth (SAG) on a polished plateau-patterned sapphire substrate (PP-PSS), on which aluminum nitride (AlN) buffer layers are deposited under the same deposition conditions. The SAG of GaN was only observed [...] Read more.

This study provides experimental evidence regarding the mechanism of gallium nitride (GaN) selective-area growth (SAG) on a polished plateau-patterned sapphire substrate (PP-PSS), on which aluminum nitride (AlN) buffer layers are deposited under the same deposition conditions. The SAG of GaN was only observed on the plateau region of the PP-PSS, irrespective of the number of growth cycles. Indirect samples deposited on the bare c-plane substrate were prepared to determine the difference between the AlN buffer layers in the plateau region and silicon oxide (

{SiO}_{2}

). The AlN buffer layer in the plateau region exhibited a higher surface energy, and its crystal orientation is indicated by AlN [001]. In contrast, regions other than the plateau region did not exhibit crystallinity and presented lower surface energies. The direct analysis results of PP-PSS using transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) are similar to the results of the indirect samples. Therefore, under the same conditions, the GaN SAG of the deposited layer is related to crystallinity, crystal orientation, and surface energy. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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10 pages, 3334 KiB

Open AccessArticle

The Effect of Periodic Duty Cyclings in Metal-Modulated Epitaxy on GaN:Mg Film

by Jun Fang, Wenxian Yang, Xue Zhang, Aiqin Tian, Shulong Lu, Jianping Liu and Hui Yang

Materials 2023, 16(4), 1730; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16041730 - 20 Feb 2023

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Abstract

Metal modulation epitaxy (MME) is a technique in which metal beams (Al, Ga, In, and Mg) are switched on and off in short periods in an RF MBE system while a continuous nitrogen plasma beam is kept on. We systematically studied the effect [...] Read more.

Metal modulation epitaxy (MME) is a technique in which metal beams (Al, Ga, In, and Mg) are switched on and off in short periods in an RF MBE system while a continuous nitrogen plasma beam is kept on. We systematically studied the effect of periodic duty cycling on the morphology, crystalline quality, Mg doping concentration, and electrical properties of GaN:Mg films grown by MME. When the metal shutter duty cycling is 20 s open/10 s close, the sample has smooth surface with clear steps even with Mg doping concentration higher than 1 × 10²⁰ cm⁻³. The RMS roughness is about 0.5 nm. The FWHM of (002) XRD rocking curve is 230 arcsec and the FWHM of (102) XRD rocking curve is 260 arcsec. As result, a hole concentration of 5 × 10¹⁸ cm⁻³ and a resistivity of 1.5 Ω·cm have been obtained. The hole concentration increases due to the incorporation of surface accumulated Mg dopants into suitable Ga substitutional sites with minimal formation of compensatory defects. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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12 pages, 2797 KiB

Open AccessEditor’s ChoiceArticle

Polarization Doping in a GaN-InN System—Ab Initio Simulation

by Ashfaq Ahmad, Pawel Strak, Pawel Kempisty, Konrad Sakowski, Jacek Piechota, Yoshihiro Kangawa, Izabella Grzegory, Michal Leszczynski, Zbigniew R. Zytkiewicz, Grzegorz Muziol, Eva Monroy, Agata Kaminska and Stanislaw Krukowski

Materials 2023, 16(3), 1227; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16031227 - 31 Jan 2023

Viewed by 1762

Abstract

Polarization doping in a GaN-InN system with a graded composition layer was studied using ab initio simulations. The electric charge volume density in the graded concentration part was determined by spatial potential dependence. The emerging graded polarization charge was determined to show that [...] Read more.

Polarization doping in a GaN-InN system with a graded composition layer was studied using ab initio simulations. The electric charge volume density in the graded concentration part was determined by spatial potential dependence. The emerging graded polarization charge was determined to show that it could be obtained from a polarization difference and the concentration slope. It was shown that the GaN-InN polarization difference is changed by piezoelectric effects. The polarization difference is in agreement with the earlier obtained data despite the relatively narrow bandgap for the simulated system. The hole generation may be applied in the design of blue and green laser and light-emitting diodes. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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11 pages, 1969 KiB

Open AccessArticle

The Effect of Nitridation on Sputtering AlN on Composited Patterned Sapphire Substrate

by Yi Zhang, Guangmin Zhu, Jiangbo Wang and Zichun Le

Materials 2023, 16(3), 1104; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16031104 - 27 Jan 2023

Cited by 2 | Viewed by 1624

Abstract

Here, we report on the epitaxial growth of GaN on patterned SiO₂-covered cone-shaped patterned sapphire surfaces (PSS). Physical vapor deposition (PVD) AlN films were used as buffers deposited on the SiO₂-PSS substrates. The gallium nitride (GaN) growth on these [...] Read more.

Here, we report on the epitaxial growth of GaN on patterned SiO₂-covered cone-shaped patterned sapphire surfaces (PSS). Physical vapor deposition (PVD) AlN films were used as buffers deposited on the SiO₂-PSS substrates. The gallium nitride (GaN) growth on these substrates at different alternating radio frequency (RF) power and nitridation times was monitored with sequences of scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging results. The SEM and AFM show the detail of the crystalline process from different angles. Our findings show that the growth mode varies according to the deposition condition of the AlN films. We demonstrate a particular case where a low critical alternating current (AC) power is just able to break SiO₂ covalent bonds, enabling the growth of GaN on the sides of the patterns. Furthermore, we show that by using the appropriate nitridation condition, the photoluminescence (PL) integral and peak intensities of the blue light epi-layer were enhanced by more than 5% and 15%, respectively. It means the external quantum efficiency (EQE) of epitaxial structures is promoted. The screw dislocation density was reduced by 65% according to the X-ray diffraction (XRD) spectra. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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17 pages, 3629 KiB

Open AccessEditor’s ChoiceArticle

Synthesis, Structural and Magnetic Properties of Cobalt-Doped GaN Nanowires on Si by Atmospheric Pressure Chemical Vapor Deposition

by Zhe Chuan Feng, Yu-Lun Liu, Jeffrey Yiin, Li-Chyong Chen, Kuei-Hsien Chen, Benjamin Klein and Ian T. Ferguson

Materials 2023, 16(1), 97; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16010097 - 22 Dec 2022

Cited by 1 | Viewed by 2003

Abstract

GaN nanowires (NWs) grown on silicon via atmospheric pressure chemical vapor deposition were doped with Cobalt (Co) by ion implantation, with a high dose concentration of 4 × 10¹⁶ cm⁻², corresponding to an average atomic percentage of ~3.85%, and annealed [...] Read more.

GaN nanowires (NWs) grown on silicon via atmospheric pressure chemical vapor deposition were doped with Cobalt (Co) by ion implantation, with a high dose concentration of 4 × 10¹⁶ cm⁻², corresponding to an average atomic percentage of ~3.85%, and annealed after the implantation. Co-doped GaN showed optimum structural properties when annealed at 700 °C for 6 min in NH₃ ambience. From scanning electron microscopy, X-ray diffraction, high resolution transmission electron microscope, and energy dispersive X-ray spectroscopy measurements and analyses, the single crystalline nature of Co-GaN NWs was identified. Slight expansion in the lattice constant of Co-GaN NWs due to the implantation-induced stress effect was observed, which was recovered by thermal annealing. Co-GaN NWs exhibited ferromagnetism as per the superconducting quantum interference device (SQUID) measurement. Hysteretic curves with Hc (coercivity) of 502.5 Oe at 5 K and 201.3 Oe at 300 K were obtained. Applied with a magnetic field of 100 Oe, the transition point between paramagnetic property and ferromagnetic property was determined at 332 K. Interesting structural and conducive magnetic properties show the potential of Co-doped GaN nanowires for the next optoelectronic, electronic, spintronic, sensing, optical, and related applications. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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