Papers by Theeradetch Detchprohm
1.2-kV Vertical GaN PIN Rectifier With Ion-Implanted Floating Guard Rings
IEEE Transactions on Electron Devices, 2023
Realizing crack-free high-aluminum-mole-fraction AlGaN on patterned GaN beyond the critical layer thickness
Journal of Applied Physics, Feb 16, 2022
Wide-bandgap III-nitride heterostructures are required for a variety of device applications. Howe... more Wide-bandgap III-nitride heterostructures are required for a variety of device applications. However, this alloy system has a large lattice constant and thermal expansion coefficient mismatch that limits the alloy composition and layer thickness for many heteroepitaxial device structures. Consequently, various methods have been devised to allow the heteroepitaxial growth of AlInGaN heterostructures to accommodate this inherent strain. In this work, we describe a non-planar-growth approach that enables the deposition of crack-free high-Al-mole-fraction AlxGa1−xN on patterned GaN/sapphire templates and bulk GaN substrates with large-area mesas. We have studied the effects of the patterned mesa width, the mesa etch depth, and the gap between the mesas on the heteroepitaxy of AlxGa1−xN superlattices with an average Al molar fraction 0.11 < x¯ < 0.21 and non-planar overgrowth growth thicknesses up to 3.5 μm. Similar to the planar growth approach, increasing the thickness and Al mole fraction of the AlxGa1−xN superlattices leads to surface cracking when exceeding the critical layer thickness. However, limiting the mesa dimension in one direction enables strain mitigation and drastically increases the critical layer thickness. Additionally, larger etch depths of the mesas increase the Al alloy composition and thickness for crack-free AlGaN heteroepitaxy whereas the gap in between the mesas seems to have no crucial influence. We demonstrate that the Al alloy composition and layer thicknesses of such heterostructures can be increased far beyond the critical layer thickness for planar growth and demonstrate the growth of a crack-free full AlxGa1−xN/GaN quantum-well laser heterostructure designed for operation at ∼370 nm.
Magnesium doping profile control in p-GaN layers grown by metalorganic chemical vapor deposition
Journal of Crystal Growth, 2023
Journal of Applied Physics, Mar 14, 2022
A top-illuminated deep-ultraviolet (DUV) Al0.6Ga0.4N p-in avalanche photodiode (APD) structure wa... more A top-illuminated deep-ultraviolet (DUV) Al0.6Ga0.4N p-in avalanche photodiode (APD) structure was designed, grown by metalorganic chemical vapor deposition on an AlN bulk substrate and on two different quality AlN/sapphire templates, and APDs were fabricated and tested. The APD devices with a circular diameter of 20 µm have demonstrated a distinctive reverse-bias breakdown behavior. The reverse breakdown voltage of the APDs is ~-140V, which corresponds to breakdown electric field of 6~6.2 MV/cm for the Al0.6Ga0.4N material as estimated by Silvaco TCAD simulation. The APDs grown on the AlN bulk substrate shows the lowest leakage current density of <1×10-8 A/cm 2 (at low reverse bias) compared to that of the devices grown on the AlN templates. From the photocurrent measurement, a maximum gain (current limited) of 1.2×10 4 is calculated. The average temperature coefficients of the breakdown voltage are negative for APD devices fabricated from both the AlN bulk substrate and the AlN templates, but these data show that the coefficient is the least negative for the APD devices grown on the lowdislocation-density AlN bulk substrate. Significance Statement We present new data on the properties of deep-UV AlxGa1-xN p-in avalanche photodiodes grown on bulk AlN substrates operating at ~250 nm. Few published reports currently exist for such devices and these previous reports lack a full description of the electrical properties. This paper describes the structure and growth of these devices compared with devices grown on sapphire
Applied Physics Letters, Nov 30, 1992
A method of manufacturing two sapphireless layers (3a, 3b) at one time made of Group III nitride ... more A method of manufacturing two sapphireless layers (3a, 3b) at one time made of Group III nitride compound semicon ductor satisfying the formula AlGaIn-N, inclusive of x=0, y=0, and x=y=0, and a LED (10) utilizing one of the Semiconductor layers (3a, 3b) as a substrate (3) includes the
1.2-kV Vertical GaN PIN Rectifier With Ion-Implanted Floating Guard Rings
IEEE Transactions on Electron Devices, 2023
Journal of Crystal Growth, Oct 1, 2017
We have investigated the microstructure of B x Al 1-x N films grown by flow-modulated epitaxy at ... more We have investigated the microstructure of B x Al 1-x N films grown by flow-modulated epitaxy at 1010 o C, with B/(B+Al) gas-flow ratios ranging from 0.06 to 0.18. The boron content obtained from X-ray diffraction (XRD) patterns ranges from x = 0.02 to 0.09. On the other hand, boron content deduced from the aluminum signal in the Rutherford backscattering spectra (RBS) ranges x = 0.06 to 0.16, closely following gas-flow ratios. Transmission electron microscopy indicates the sole presence of wurtzite crystal structure in the BAlN films, and a tendency towards columnar growth for B/(B+Al) gas-flow ratios below 0.12. For higher ratios, the BAlN films exhibit a tendency towards twin formation and finer microstructure. Electron energy loss spectroscopy has been used to profile spatial variations in the composition of the films. The RBS data suggest that the incorporation of B is highly efficient for our growth method, while the XRD data indicate that the epitaxial growth may be limited by a solubility limit in the crystal phase at
Realizing crack-free high-aluminum-mole-fraction AlGaN on patterned GaN beyond the critical layer thickness
Journal of Applied Physics, Feb 16, 2022
Wide-bandgap III-nitride heterostructures are required for a variety of device applications. Howe... more Wide-bandgap III-nitride heterostructures are required for a variety of device applications. However, this alloy system has a large lattice constant and thermal expansion coefficient mismatch that limits the alloy composition and layer thickness for many heteroepitaxial device structures. Consequently, various methods have been devised to allow the heteroepitaxial growth of AlInGaN heterostructures to accommodate this inherent strain. In this work, we describe a non-planar-growth approach that enables the deposition of crack-free high-Al-mole-fraction AlxGa1−xN on patterned GaN/sapphire templates and bulk GaN substrates with large-area mesas. We have studied the effects of the patterned mesa width, the mesa etch depth, and the gap between the mesas on the heteroepitaxy of AlxGa1−xN superlattices with an average Al molar fraction 0.11 &lt; x¯ &lt; 0.21 and non-planar overgrowth growth thicknesses up to 3.5 μm. Similar to the planar growth approach, increasing the thickness and Al mole fraction of the AlxGa1−xN superlattices leads to surface cracking when exceeding the critical layer thickness. However, limiting the mesa dimension in one direction enables strain mitigation and drastically increases the critical layer thickness. Additionally, larger etch depths of the mesas increase the Al alloy composition and thickness for crack-free AlGaN heteroepitaxy whereas the gap in between the mesas seems to have no crucial influence. We demonstrate that the Al alloy composition and layer thicknesses of such heterostructures can be increased far beyond the critical layer thickness for planar growth and demonstrate the growth of a crack-free full AlxGa1−xN/GaN quantum-well laser heterostructure designed for operation at ∼370 nm.
Magnesium doping profile control in p-GaN layers grown by metalorganic chemical vapor deposition
Journal of Crystal Growth, 2023
Journal of Applied Physics, Mar 14, 2022
A top-illuminated deep-ultraviolet (DUV) Al0.6Ga0.4N p-in avalanche photodiode (APD) structure wa... more A top-illuminated deep-ultraviolet (DUV) Al0.6Ga0.4N p-in avalanche photodiode (APD) structure was designed, grown by metalorganic chemical vapor deposition on an AlN bulk substrate and on two different quality AlN/sapphire templates, and APDs were fabricated and tested. The APD devices with a circular diameter of 20 µm have demonstrated a distinctive reverse-bias breakdown behavior. The reverse breakdown voltage of the APDs is ~-140V, which corresponds to breakdown electric field of 6~6.2 MV/cm for the Al0.6Ga0.4N material as estimated by Silvaco TCAD simulation. The APDs grown on the AlN bulk substrate shows the lowest leakage current density of <1×10-8 A/cm 2 (at low reverse bias) compared to that of the devices grown on the AlN templates. From the photocurrent measurement, a maximum gain (current limited) of 1.2×10 4 is calculated. The average temperature coefficients of the breakdown voltage are negative for APD devices fabricated from both the AlN bulk substrate and the AlN templates, but these data show that the coefficient is the least negative for the APD devices grown on the lowdislocation-density AlN bulk substrate. Significance Statement We present new data on the properties of deep-UV AlxGa1-xN p-in avalanche photodiodes grown on bulk AlN substrates operating at ~250 nm. Few published reports currently exist for such devices and these previous reports lack a full description of the electrical properties. This paper describes the structure and growth of these devices compared with devices grown on sapphire
Applied Physics Letters, Nov 30, 1992
A method of manufacturing two sapphireless layers (3a, 3b) at one time made of Group III nitride ... more A method of manufacturing two sapphireless layers (3a, 3b) at one time made of Group III nitride compound semicon ductor satisfying the formula AlGaIn-N, inclusive of x=0, y=0, and x=y=0, and a LED (10) utilizing one of the Semiconductor layers (3a, 3b) as a substrate (3) includes the
Journal of Crystal Growth, Oct 1, 2017
We have investigated the microstructure of B x Al 1-x N films grown by flow-modulated epitaxy at ... more We have investigated the microstructure of B x Al 1-x N films grown by flow-modulated epitaxy at 1010 o C, with B/(B+Al) gas-flow ratios ranging from 0.06 to 0.18. The boron content obtained from X-ray diffraction (XRD) patterns ranges from x = 0.02 to 0.09. On the other hand, boron content deduced from the aluminum signal in the Rutherford backscattering spectra (RBS) ranges x = 0.06 to 0.16, closely following gas-flow ratios. Transmission electron microscopy indicates the sole presence of wurtzite crystal structure in the BAlN films, and a tendency towards columnar growth for B/(B+Al) gas-flow ratios below 0.12. For higher ratios, the BAlN films exhibit a tendency towards twin formation and finer microstructure. Electron energy loss spectroscopy has been used to profile spatial variations in the composition of the films. The RBS data suggest that the incorporation of B is highly efficient for our growth method, while the XRD data indicate that the epitaxial growth may be limited by a solubility limit in the crystal phase at
HVPE growth of GaN bulk single crystal
High Al mole fraction crack-free AlGaN on GaN for UV laser diodes by a non-planar growth approach
HVPE growth of GaN bulk single crystal
In absence of piezoelectric polarization along the growth axis, aand m-plane green GaInN light em... more In absence of piezoelectric polarization along the growth axis, aand m-plane green GaInN light emitting diodes manifest stable emission wavelength-independent of the injection current density. The shift of the dominant wavelength is less than 8 nm when varying the forward current density from 0.1 to 38 A/cm 2. Furthermore, the light emitted from the growth surface of such non-polar structures shows a very degree of linear polarization. This is attributed to a strong valance band splitting in such anisotropically strained wurtzite GaInN quantum wells. Such light emitting diodes show a high potential for energy efficient display applications.
High Al mole fraction crack-free AlGaN on GaN for UV laser diodes by a non-planar growth approach
Japanese Journal of Applied Physics, May 15, 2001
We report on a visible-blind AlGaN/GaN heterobipolar phototransistor with low threading dislocati... more We report on a visible-blind AlGaN/GaN heterobipolar phototransistor with low threading dislocation density, fabricated by organometallic vapor phase epitaxy using the low-temperature interlayer technique. The dark current at room temperature was as low as 34.6 pA/mm 2 at 3 V and the responsivity was 160 A/W under 0.78 nW/cm 2 illumination. The high-temperature device performance up to 200 • C was marked by the exponential evolution of the dark current under the influence of a deep defect near 459 meV. Also, photoinduced transient spectroscopy between 50 • C and 175 • C yielded evidence of defects at about 93 meV, 137 meV and 205 meV energies, which caused a long-lasting photocurrent after weak-intensity illumination.
Development of Direct Green Emitting LEDs
Advancement in nitride epitaxy allows the development of direct emitting green LEDs. Crucial to t... more Advancement in nitride epitaxy allows the development of direct emitting green LEDs. Crucial to that is the realization of tremendous defect reduction potential by nano-patterned epitaxy. We present our development in polar semi- and non-polar growth orientation.
Applied Physics Express, Nov 9, 2015
We compare the performance characteristics of Al 0.05 Ga 0.95 N UV avalanche photodiodes (APDs) g... more We compare the performance characteristics of Al 0.05 Ga 0.95 N UV avalanche photodiodes (APDs) grown on different substrates. UV-APDs grown on a free-standing GaN substrate show lower dark-current densities for all fabricated mesa sizes than similar UV-APDs grown on a GaN/sapphire template. In addition, a stable avalanche gain higher than 5 ' 10 5 and a significant increase in the responsivity of UV-APDs grown on a freestanding GaN substrate are observed. We believe that the high crystalline quality of Al 0.05 Ga 0.95 N UV-APDs grown on a free-standing GaN substrate with low dislocation density is responsible for the observed low leakage currents, high performance characteirstics, and reliability of the devices.
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Papers by Theeradetch Detchprohm