Single-Crystal Growth and Characterization of β-Ga2O3 (1 0 0) for GaP/Ga2O3 Heterostructures by Hydride Vapor Phase Epitaxy Dhandapani Dhanabalan, Raja Sakthivel, Moorthy Babu Sridharan, Balaji Manavaimaran, Axel Strömberg, Lourdudoss Sebastian, Yan‐Ting Sun Physica Status Solidi A Applications and Materials Science, 2025 Single‐crystal growth of (100) β ‐Ga 2 O 3 and the attempt to grow GaP on it by hydride vapor phase epitaxy (HVPE) is been described. The phase purity and (100) orientation of the crystal is confirmed by X‐ray diffraction (XRD). The selected area electron diffraction pattern confirms the monoclinic structure with a C2/m space group of β ‐Ga 2 O 3 . Raman results reveal the stretching and bending vibrations of GaO and GaOGa octahedrons, respectively. The wafer exhibits ≈80% optical transmission and surface roughness of ≈5 nm. GaP layers are grown on (100)‐oriented β ‐Ga 2 O 3 substrates by HVPE. The GaP/ β ‐Ga 2 O 3 heterostructures are characterized using XRD and Raman spectroscopy. Diffraction peak at (111) confirms the zinc blende phase of GaP. The longitudinal optical (405 cm −1 ) and transverse optical (368 cm −1 ) phonon modes in the Raman spectra confirm the crystalline GaP. Further optimization is expected to enhance the crystalline quality of the GaP layer on the Ga 2 O 3 wafer. The potential of GaP/(100) β ‐Ga 2 O 3 heterostructures are highlighted.
Phase-matching in terahertz quantum cascade laser sources based on Cherenkov difference-frequency mixing Wolfhard Oberhausen, Iaroslav Lubianskii, Gerhard Boehm, Axel Strömberg, Balaji Manavaimaran, Dominik Burghart, Yan-Ting Sun, Mikhail A. Belkin APL Photonics, 2023 Terahertz quantum cascade laser sources based on intra-cavity Cherenkov difference-frequency generation in dual-wavelength mid-infrared quantum cascade lasers are currently the only monolithic semiconductor laser technology that can deliver continuous-wave coherent terahertz output at room temperature. Because the Cherenkov difference-frequency generation process enables terahertz radiation generation and extraction across a wide range of frequencies, it is often assumed that phase-matching conditions for this process are automatically fulfilled. We theoretically analyze and experimentally demonstrate that phase-matching plays an important role in these devices, and significant improvements in terahertz power output can be achieved by adjusting the waveguide configuration of the quantum cascade lasers to provide better phase-matching.
Epitaxial Lateral Overgrowth of GaAsP for III-V/Si-Based Photovoltaics Axel Strömberg, Balaji Manavaimaran, Lakshman Srinivasan, Sebastian Lourdudoss, Yan-Ting Sun Physica Status Solidi A Applications and Materials Science, 2023 GaAsP/Si with high crystalline quality fabricated by cost‐effective heteroepitaxial technology is a promising pathway for realizing low‐cost Si‐based tandem solar cell with efficiency higher than 30%. Herein, hydride vapor‐phase epitaxy is used to perform selective area growth of GaAsP with high lateral coverage, referred to as epitaxial lateral overgrowth (ELOG). The ELOG is performed on GaAs‐based substrates as a prestudy, followed by GaAs/Si and GaAsP/Si seed wafers employing chemical mechanical polishing to fabricate full 2″ GaAsP/Si templates. These are subsequently used to grow and process GaAsP/Si pn‐junction structures for electrical characterization. The ELOG GaAsP is studied by spatially resolved photoluminescence (PL) mapping and high‐resolution X‐ray diffraction measurements. PL analysis of the GaAsP/GaAs ELOG samples reveals an enhanced P‐incorporation during lateral growth of GaAsP. This is also observed for the GaAsP/Si ELOG templates along with evidence of improved material quality, clearly distinguishing the laterally grown GaAsP from the planar growth directly above the Si substrate. Leakage pathways causing reduced electrical performance of the ELOG GaAsP/Si pn‐junction structures are identified.
Investigation of OP-GaP Grown on OP-GaAs Templates Using Nondestructive Reciprocal Space Mapping Balaji Manavaimaran, Axel Strömberg, Vladimir L. Tassev, Shivashankar R. Vangala, Myriam Bailly, Arnaud Grisard, Bruno Gérard, Sebastian Lourdudoss, Yan-Ting Sun Crystals, 2023 Orientation-patterned gallium phosphide (OP-GaP) has been grown heteroepitaxially on OP gallium arsenide (GaAs) templates using hydride vapor phase epitaxy (HVPE). The effect of OP-GaAs template fabrication methods of epitaxial-inversion and wafer bonding on the heteroepitaxial OP-GaP growth has been investigated. OP-GaP layers with a growth rate of up to 35 µm/h and excellent domain fidelity were obtained. The growth rate and the domain fidelity have been revealed/studied by scanning electron microscope (SEM). In addition, we demonstrate that the crystalline quality of the individual domains, namely, the substrate-oriented domains (ODs) and the inverted domains (IDs), can be investigated by high-resolution x-ray diffraction reciprocal space mapping (HRXRDRSM), which can also indicate the domain fidelity. Attempts to increase the growth rate and improve the domain fidelity by increasing the III and V group precursors resulted in either an increase in the growth rate in the OP-GaP layers grown on epitaxial inversion OP-GaAs template at the expense of the domain crystalline quality and fidelity or an improvement in the crystalline quality of the domains at the expense of the growth rate in the OP-GaP layers grown on wafer-bonded OP-GaAs templates. In the case of OP-GaP grown on OP-GaAs templates prepared by epitaxial inversion, the crystalline quality of the ODs is better than that of the IDs, but it shows that the quality of the inverted layer in the template influences the quality and fidelity of the grown domains. To the authors’ knowledge, exploitation of HRXRDRSM studies on OP-GaP to establish the crystalline quality of its individual domains (ODs and IDs) is the first of its kind. OP-ZnSe grown on OP-GaAs templates has also been included in this study to further emphasize the potential of this method. We propose from this study that once the growth rate is optimized from SEM studies, HRXRDRSM analysis alone can be used to assess the structural quality and to infer the domain fidelity of the OP structures.
Semi-insulating InP:Fe growth by hydride vapor phase epitaxy for advanced buried heterostructure quantum cascade lasers Axel Strömberg, Balaji Manavaimaran, Xiaodan Pang, Richard Schatz, Oskars Ozolins, Sebastian Lourdudoss, David Stark, Mattias Beck, Giacomo Scalari, Jérôme Faist, Jae Ha Ryu, Luke J. Mawst, Dan Botez, Robert Marsland, Grégory Maisons, Mathieu Carras, Yan-Ting Sun Proceedings of SPIE the International Society for Optical Engineering, 2023 Buried heterostructure quantum cascade lasers (BH-QCLs) operating at high temperature in mid-infrared (MIR) to THz spectral range are desired for chemical sensing and free-space optical communication (FOC). In this work, Fe doped semi-insulating InP (SI-InP) regrowth is demonstrated in a hydride vapor phase epitaxy (HVPE) reactor for advanced MIR and THz BH-QCLs grown by MBE and MOCVD. SI-InP regrowth is implemented in THz QCL pillar arrays and narrow width and reverse-taper MIR BH-QCLs for efficient heat dissipation. By exploiting SI-InP regrowth, the parasitic capacitance in MIR distributed feedback BH-QCL can be suppressed, which is exploited for high speed FOC application.
Heteroepitaxial Growth of GaP Photocathode by Hydride Vapor Phase Epitaxy for Water Splitting and CO2 Reduction Axel Strömberg, Yanqi Yuan, Feng Li, Balaji Manavaimaran, Sebastian Lourdudoss, Peng Zhang, Yanting Sun Catalysts, 2022 Heteroepitaxial Zn-doped p-GaP was grown on (001) GaAs, (001) Si and (111) Si substrates by hydride vapor phase epitaxy for solar-driven photoelectrochemical applications of hydrogen generation by water splitting and CO2 reduction. Growth of GaP on Si was realized through the implementation of a low-temperature buffer layer, and the morphology and crystalline quality were enhanced by optimizing the precursor flows and pre-heating ambient substrate. The p-GaP/GaAs and p-GaP/Si samples were processed to photoelectrodes with an amorphous TiO2 coating for CO2 reduction and a combination of TiO2 layer and mesoporous tungsten phosphide catalyst for water splitting. P-GaP/GaAs with suitable Zn-doping concentration exhibited photoelectrochemical performance comparable to homoepitaxial p-GaP/GaP for water splitting and CO2 reduction. Degradation of photocurrent in p-GaP/Si photoelectrodes is observed in PEC water splitting due to the high density of defects arising from heteroepitaxial growth.
Growth of AlN nanostructure on GaN using MOCVD R. Loganathan, R. Ramesh, M. Jayasakthi, K. Prabakaran, B. Kuppulingam, M. Sankaranarayanan, M. Balaji, P. Arivazhagan, Subra Singh, K. Baskar Aip Conference Proceedings, 2015
Effect of Al-mole fraction in AlxGa1-xN grown by MOCVD M. Jayasakthi, R. Ramesh, K. Prabakaran, R. Loganathan, B. Kuppulingam, M. Balaji, P. Arivazhagan, S. Sankaranarayanan, Shubra Singh, K. Baskar Aip Conference Proceedings, 2014
Growth and Characterization of AlInGaN/AIN/GaN grown by MOCVD Ravi Loganathan, Mathaiyan Jayasakthi, Kandhasamy Prabakaran, Raju Ramesh, Ponnusamy Arivazhagan, Boopathi kuppulingam, Subramanian Sankaranarayanan, Manavaimaran Balaji, Shubra Singh, Krishnan Baskar Environmental Science and Engineering, 2014
Growth and characterization of AlxGa1-xN on GaN/Al2O3 Mathaiyan Jayasakthi, Raju Ramesh, Ponnusamy Arivazhagan, Ravi Loganathan, Kandhasamy Prabakaran, Manavaimaran Balaji, Krishnan Baskar Proceedings of SPIE the International Society for Optical Engineering, 2012
Modifications of defects concentrations induced by ammonia flow rate and its effects on gallium nitride grown by MOCVD Materials Research Society Symposium Proceedings, 2010
