A5069096575- GaN-based semiconductor devices and materials
- Semiconductor Quantum Structures and Devices
- Ga2O3 and related materials
- Semiconductor materials and devices
- ZnO doping and properties
- Semiconductor Lasers and Optical Devices
- Metal and Thin Film Mechanics
- Acoustic Wave Resonator Technologies
- Nanowire Synthesis and Applications
- Spectroscopy and Laser Applications
- Photocathodes and Microchannel Plates
- Plasma Diagnostics and Applications
- Gas Sensing Nanomaterials and Sensors
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Semiconductor Detectors and Materials
- Semiconductor materials and interfaces
- Quantum and electron transport phenomena
- Superconducting and THz Device Technology
- Advanced Optical Sensing Technologies
- Optical Coatings and Gratings
- Electrostatic Discharge in Electronics
- Advanced Photocatalysis Techniques
- Strong Light-Matter Interactions
- Laser Design and Applications
- Physics of Superconductivity and Magnetism
Institute of High Pressure Physics
2016-2025
Polish Academy of Sciences
2016-2025
TopGaN (Poland)
2005-2017
Paul Drude Institute for Solid State Electronics
2013-2016
Forschungsverbund Berlin
2016
TU Wien
2007
Unlike non-polar semiconductors such as silicon, the broken inversion symmetry of wide-bandgap semiconductor gallium nitride (GaN) leads to a large electronic polarization along unique crystal axis
Double-barrier GaN resonant tunneling diodes with AlGaN barriers were fabricated on bulk (0001) single-crystal substrates. Layers grown using molecular-beam epitaxy a rf plasma nitrogen source. Single of 6μm diameter prepared by inductively coupled reactive ion etching. For many clear negative differential resistance is observed around 2V peak currents 10kA∕cm2 and peak-to-valley ratio about 2 at room temperature. Its observation does not depend specific conditions measurement; however, it...
The progress in the growth of nitride-based laser diodes (LDs) made by plasma-assisted molecular beam epitaxy (PAMBE) is reviewed. In this work we describe GaN and InGaN peculiarities, p-type doping efficiency, properties quantum wells (QWs) grown PAMBE. We demonstrate continuous wave (cw) LDs operating range from 410 to 482 nm. These were on low dislocation (0 0 1) c-plane bulk substrate, which allow one fabricate cw with a lifetime exceeding 2000 h. Also, ultraviolet at 388 nm (2 −2...
Solid state devices based on InGaN\penalty1000-\hskip0ptalloys have revolutionized lighting applications and resulted in huge energy savings. Here, the authors investigate growth of single monolayer InGaN layers by well-designed experiments, advanced characterization, theoretical modeling. Specifically, they show that films is self-limited with respect to thickness chemical composition, but shows a unique ordering absent conventional films. The origin self-limitation novel surface...
Blue and violet light-emitting devices based on III-nitrides caused an ongoing revolution in general lighting. One of the highly deliberated discussions this field is devoted to problem called "green gap", which a lack efficient emitters spectral regime. reasons behind insufficient internal quantum efficiency (IQE) green III-nitride related confined Stark effect. In paper we present counterintuitive feature well systems with large built-in electric that leads huge enhancement IQE. We show,...
We demonstrate true-blue 450 nm tunnel junction (TJ) laser diodes (LDs) grown by plasma-assisted molecular beam epitaxy (PAMBE). The absence of hydrogen during PAMBE growth allows us to achieve TJs with low resistance. compare TJ LDs standard construction p-type metal contact. For both types LD, the threshold current density is around 3 kA/cm2 and slope efficiency 0.5 W/A. do not observe any significant changes in optical losses differential gain compared LDs. resistivity for densities...
We report on the InGaN multiquantum laser diodes (LDs) made by rf plasma-assisted molecular beam epitaxy (PAMBE). The operation at 408nm is demonstrated room temperature with pulsed current injections using 50ns pulses 0.25% duty cycle. threshold density and voltage for LDs cleaved uncoated mirrors are 12kA∕cm2 (900mA) 9V, respectively. High output power of 0.83W obtained during pulse 3.6A 9.6V bias slope efficiency 0.35W∕A. structures deposited high-pressure-grown low dislocation bulk GaN...
The results on growth and magnetotransport characterization of AlGaN∕GaN heterostructures obtained by plasma assisted molecular beam epitaxy dislocation-free (below 100cm−2) GaN high pressure synthesized bulk substrates are presented. record mobilities the two dimensional electron gas (2DEG) exceeding 100000cm2∕Vs at liquid helium temperature 2500cm2∕Vs room reported. An analysis field conductivity tensor components allowed us to discuss main scattering mechanisms confirm unambiguously 2DEG...
We report on optically pumped lasing at 500 nm InGaN laser structures grown by plasma assisted molecular beam epitaxy. The were under group III-rich conditions bulk (0001) GaN substrates. influence of the nitrogen flux and growth temperature indium content layers was studied. demonstrate that elevated temperatures, where appreciable dissociation rate for In-N bonds is observed, increases with increasing flux. show higher temperatures improves optical quality quantum wells, which crucial...
The influence of InxGa1−xN waveguide on the properties blue (λ = 450 nm) laser diodes grown by plasma-assisted molecular beam epitaxy was studied. threshold current density reduced 50% (to 3.6 kA/cm2) when indium content increased from x 0.04 to 0.08. This is explained a substantial enhancement optical confinement factor for high-In-content waveguide, which increases differential modal gain. Furthermore, we observed decrease in losses Mg-doped layers were separated active region thicker...
Abstract A novel design consisting of a thick InGaN waveguide is proposed to fully eliminate leakage the GaN substrate in nitride laser diodes. The based on effective refractive index engineering and does not require commonly used AlGaN claddings. conditions required optical are discussed. Experimental results from eight blue diodes with different indium contents thicknesses grown by plasma-assisted molecular beam epitaxy presented validate theoretical results.
We demonstrate a stack of two III-nitride laser diodes (LDs) interconnected by tunnel junction grown plasma-assisted molecular beam epitaxy. Hydrogen-free growth is used to obtain as-grown p-type conductivity essential for buried junctions (TJ). show the impact design junction. In particular, we that, apart from beneficial piezoelectric polarization inside TJ, heavy doping reduces differential resistivity even further. The device starts lase at wavelength 459 nm with slope efficiency (SE)...
The design of the active region is one most crucial problems to address in light emitting devices (LEDs) based on III-nitride, due spatial separation carriers by built-in polarization. Here, we studied radiative transitions InGaN-based LEDs with various quantum well (QW) thicknesses-2.6, 6.5, 7.8, 12, and 15 nm. In case thinnest QW, observed a typical effect screening field manifested blue shift electroluminescence spectrum at high current densities, whereas 6.5 7.8 nm QWs exhibited...
We report on III-nitride-based micro-light-emitting diodes (µLEDs) operating at 450 nm wavelength with diameters down to 2 µm. Devices a standard LED structure followed by tunnel junction were grown plasma-assisted molecular beam epitaxy. The emission size of µLEDs was defined shallow He+ implantation the region. ion process allows create flat devices, applicable further epitaxial regrowth. shift current density for maximum external quantum efficiency as function diameter observed. This...
Despite the ubiquity of semiconductor-based emitters in optoelectronic devices we use every day, obstacles still remain to unlock their full potential. One these lies long-wavelength GaN-based laser diodes (LDs). It is common knowledge that InGaN quantum wells (QWs) exhibit extremely large built-in polarization, which helps obtain emission light-emitting diodes, thanks quantum-confined Stark effect. However, this paper, it shown order achieve LDs, wide QWs might be preferential. The lasing...
We demonstrate continuous-wave operation at 411nm of InGaN multi-quantum-well laser diodes (LDs) made by plasma-assisted molecular-beam epitaxy (PAMBE). The threshold current density and voltage for these LDs are 4.2kA∕cm2 5.3V, respectively. High optical output power 60mW is achieved. fabricated on low-dislocation-density bulk GaN substrates, growth conditions which resemble liquid-phase epitaxy. show that use such substrates eliminates spiral growth, the dominant mechanism PAMBE...
Abstract In this paper we review the recent studies on wide InGaN quantum wells (QWs). QWs are known to suffer from an extremely high built-in piezoelectric polarization, which separates electron and hole wavefunctions causes quantum-confined Stark effect. We show both by means of modeling experimentally, that can have efficiency superior commonly used thin QWs. The is explained initial screening field subsequent emergence optical transitions involving excited states electrons holes, a...
We compare the optical properties of four pin diode samples differing by built-in field direction and width In0.17Ga0.83N quantum well in active layer: two diodes with standard nip layer sequences 2.6 15 nm widths inverted ordering (due to tunnel junction grown before structure) also widths. study photoluminescence photocurrent those (as a function excitation power applied voltage), revealing very different due interplay fields screening injected carriers. Out types diodes, highest...
Phosphor-coated III-nitride light-emitting diodes (III-N LEDs) are currently the most efficient sources of white light. However, standard LEDs require a direct current (DC) supply, while power in electrical grid is distributed as alternating (AC). Considerable efforts therefore devoted to development directly AC-powered semiconductor light sources. In this paper, we demonstrate bidirectional emitting diode (BD LED) that emits under positive and negative bias from same active region [1]. The...
Abstract In this work we study the growth of Light Emitting Diodes (LEDs) by Plasma Assisted MBE (PAMBE). The active LEDs region was grown to cover spectral range spanning from 415 nm 520 nm. We demonstrate efficient with highest optical power output 1.5 mW and 20 mA for For longer wavelengths observe a drop power. reduction quantum efficiency green emission can be related presence strong built‐in piezoelectric fields or increased number nonradiative recombinarion centers. (© 2009 WILEY‐VCH...
The distribution of electric field in GaN(cap)/AlGaN/GaN(buffer) transistor heterostructures with various AlGaN layer thicknesses (10, 20, and 30 nm) has been studied by contactless electroreflectance compared theoretical calculations performed for positions the Fermi-level on GaN surface. For three samples best agreement between experimental data found at same position surface (i.e., 0.55±0.05 eV below conduction band). It means that is pinned this pinning can be treated as boundary...
Recently, the use of bottom-TJ geometry in LEDs, which achieves N-polar-like alignment polarization fields conventional metal-polar orientations, has enabled enhancements LED performance due to improved injection efficiency. Here, we elucidate root causes behind enhanced efficiency by employing mature laser diode structures with optimized heterojunction GaN/In 0.17 Ga 0.83 N/GaN TJs and UID GaN spacers separate optical mode from heavily doped absorbing p-cladding regions. In such structures,...