Gallium nitride (GaN) and its allied binaries InN AIN as well their ternary compounds have gained an unprecedented attention due to wide-ranging applications encompassing green, blue, violet, ultraviolet (UV) emitters detectors (in photon ranges inaccessible by other semiconductors) high-power amplifiers. However, even the best of three binaries, GaN, contains many structural point defects caused a large extent lattice stacking mismatch with substrates. These notably affect electrical...

We demonstrate that yellow luminescence often observed in both carbon-doped and pristine GaN is the result of electronic transitions via ${\mathrm{C}}_{\mathrm{N}}\mathrm{\text{\ensuremath{-}}}{\mathrm{O}}_{\mathrm{N}}$ complex. In contrast to common isolated defects, complex energetically favorable, its calculated optical properties, such as absorption emission energies, a zero phonon line, thermodynamic transition level, all show excellent agreement with measured data. Thus, by combining...

Photoluminescence (PL) spectroscopy is a powerful tool in studying semiconductor properties and identifying point defects. Gallium nitride (GaN) remarkable material for its use new generation of bright white LEDs, blue lasers, high-power electronics. In this Tutorial, we present details PL experiments discuss possible sources mistakes. A brief analysis near-band-edge emission includes basic characterization GaN, essential findings about excitons material, the explanation less known details....

The blue and ultraviolet photoluminescence bands in Mg-doped GaN have been investigated over a wide range of temperatures excitation intensities. Redshifts the were observed with increasing temperature. underwent blueshift increased density. shifts 3.2 eV band are explained by potential fluctuation model for compensated semiconductor. In contrast, 2.8 essentially related to saturation luminescence from distant donor-acceptor pairs responsible this emission. Thermal quenching was at high an...

Steady-state photoluminescence (PL) from undoped wurtzite GaN has been studied in detail over a wide range of temperatures and excitation intensities. Both the observed steps temperature dependence PL intensity, nonlinear intensity on power for different bands are quantitatively explained by competition between recombination channels. Hole-capture cross sections, defect concentrations, thermal activation energies main acceptors estimated analysis dependencies PL.

In high-purity GaN grown by hydride vapor phase epitaxy, the commonly observed yellow luminescence (YL) band gives way to a green (GL) at high excitation intensity. We propose that GL with maximum 2.4 eV is caused transitions of electrons from conduction 0/+ level isolated ${\mathrm{C}}_{\mathrm{N}}$ defect. The YL band, related via \ensuremath{-}/0 same defect, has 2.1 and can be only for some samples. However, in less pure samples, where no observed, another 2.2 dominates photoluminescence...

A majority of the point defects in GaN that are responsible for broad photoluminescence (PL) bands remain unidentified. One them is green luminescence band (GL2) having a maximum at 2.35 eV which was observed previously undoped grown by molecular-beam epitaxy Ga-rich conditions. The same PL Mg-doped GaN, also very unique properties GL2 allowed us to reliably identify it different samples. best candidate defect causes nitrogen vacancy $({V}_{\mathrm{N}})$. We propose transitions electrons...

We have found a photoluminescence (PL) band with unusual properties in GaN. The blue band, termed as the ${\mathrm{BL}}_{C}$ has maximum at about 2.9 eV and an extremely short lifetime (shorter than 1 ns for free-electron concentration of ${10}^{18}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$). electron- hole-capture coefficients this defect-related are estimated ${10}^{\ensuremath{-}9}$...

The Be-related ultraviolet luminescence band with a maximum at about 3.38eV in GaN:Be is caused by the shallowest acceptor GaN −/0 transition level 0.113eV above valence band. luminescent properties of this were studied detail. First-principles calculations identify as BeGaONBeGa complex. These also predict deep level, 0.34eV However, we not able to find evidence for photoluminescence experiments. locked icon Physics Subject Headings (PhySH)Carrier generation & recombinationDefectsDoping...

Steady-state and transient surface photovoltage (SPV) in undoped GaN is studied vacuum air ambient at room temperature 400 K with a Kelvin probe. The results are explained within phenomenological model accounting for the accumulation of photogenerated holes surface, capture free electrons from bulk over near-surface potential barrier, emission states into bulk. Simple analytical expressions obtained compared experimental results. In particular, proposed explains logarithmic decay SPV after...

Tunable and abrupt thermal quenching of photoluminescence by increasing temperature has been observed for the blue band in high-resistivity Zn-doped GaN. The intensity dropped several orders magnitude within a few Kelvins, at which that drop occurred could be tuned changing incident light intensity. Modeling system with rate equations competing electron-hole recombination flows through three defect species, one is nonradiative deep donor, gives results consistent these observations.

Mechanisms of thermal quenching photoluminescence (PL) related to defects in semiconductors are analyzed. We conclude that the Schön-Klasens (multi-center) mechanism PL is much more common for III–V and II–VI as compared Seitz-Mott (one-center) mechanism. The temperature dependencies simulated with a phenomenological model. In its simplest version, three types included: shallow donor, an acceptor responsible PL, nonradiative center has highest recombination efficiency. case abrupt tunable...

Defect-related photoluminescence (PL) is analyzed in detail for $n$-type, $p$-type, and semi-insulating Mg-doped GaN grown by different techniques. The ultraviolet luminescence (UVL) band the dominant PL conductive $n$-type $p$-type GaN:Mg samples hydride vapor phase epitaxy (HVPE) molecular beam epitaxy. UVL undoped attributed to shallow $\mathrm{M}{\mathrm{g}}_{\mathrm{Ga}}$ acceptor with ionization energy of 223 meV. In samples, very large shifts (up 0.6 eV) are observed variation...

Abstract Photoluminescence (PL) was used to estimate the concentration of point defects in GaN. The results are compared with data from positron annihilation spectroscopy (PAS), secondary ion mass spectrometry (SIMS), and deep level transient (DLTS). Defect-related PL intensity undoped GaN grown by hydride vapor phase epitaxy increases linearly related only up 10 16 cm −3 . At higher concentrations, associated individual tends saturate, accordingly, does not directly correlate defects. For...

Two yellow luminescence bands related to different defects have been revealed in undoped GaN grown by hydride vapor phase epitaxy (HVPE). One of them, labeled YL1, has the zero-phonon line (ZPL) at 2.57 eV and band maximum 2.20 low temperature. This is ubiquitous observed metalorganic chemical deposition, either (but containing carbon with high concentration) or doped Si. Another band, YL3, ZPL 2.36 2.09 eV. Previously, fine structure this were erroneously attributed red band. Both YL1 YL3...

The intensity of defect‐related photoluminescence (PL) in semiconductors changes with temperature, and it usually decreases exponentially above some critical a process called the PL quenching. Herein, main mechanisms quenching are reviewed. Most examples given for defects GaN as most studied modern semiconductor, which has important applications technology. Peculiarities I–VII, II–VI, III–V compounds also Three basic distinguished. can be explained by Schön–Klasens mechanism, whereas very...

Defects in GaN layers grown by hydride vapor-phase epitaxy have been investigated photoelectrochemical (PEC) etching, and wet etching hot H3PO4 acid molten potassium hydroxide (KOH). Threading vertical wires (i.e., whiskers) hexagonal-shaped etch pits are formed on the etched sample surfaces PEC respectively. Using atomic-force microscopy, we find density of “whisker-like” features to be 2×109 cm−2, same value found for etch-pit samples with both KOH. This is comparable dislocation obtained...

Molecular-beam epitaxy grown AlxGa1−xN alloys covering the entire range of alloy compositions, 0⩽x⩽1, have been used to determine band gap dependence on its composition. The Al chemical composition was deduced from secondary ion mass spectroscopy and Rutherford backscattering. also inferred x-ray diffraction. extracted low temperature optical reflectance measurements which are relatively more accurate than photoluminescence. Fitting data resulted in a bowing parameter b=1.0 eV over range....

The broad photoluminescence band with a maximum at about 2.9 eV widely observed in undoped epitaxial GaN is studied as function of temperature and excitation intensity. We attribute the to transitions from shallow donor deep localized acceptor. zero-phonon transition for this 3.098 determined fine structure low temperatures. A local vibrational mode ground state an energy 36 meV found.

The effect of an ambient environment on the surface photovoltage and photoluminescence observed for GaN is studied. In air upward band bending gradually increases under UV illumination explained by photoinduced chemisorption adsorbates. Specifically, increase in negative charge consistent with transfer electrons from states or bulk to oxygen species physisorbed at surface. contrast, decreases vacuum can be desorption these species. photoadsorption photodesorption negatively charged cause...

The blue luminescence band with a maximum at 3.0 eV and the zero-phonon line 3.33 (labeled BL2) is observed in high-resistivity GaN. Under prolonged ultraviolet (UV) light exposure, BL2 transforms into yellow (YL) 2.2 eV. Our hybrid functional calculations suggest that related to hydrogen-carbon defect complex, either CNON-Hi or CN-Hi. complex creates transition level close valence band, which responsible for band. UV illumination, dissociates, leaving as byproduct source of YL (CNON CN)...

The yellow luminescence band was studied in undoped and Si-doped GaN samples by steady-state time-resolved photoluminescence. At low temperature (18 K), the zero-phonon line (ZPL) for is observed at 2.57 eV attributed to electron transitions from a shallow donor deep-level defect. higher temperatures, ZPL 2.59 emerges, which conduction same In addition ZPL, set of phonon replicas observed, caused emission phonons with energies 39.5 meV 91.5 meV. defect called YL1 center. possible identity...

In this paper, we present a comparison of exchange-tuned hybrid density functional calculations with experimental data obtained for the Zn acceptor in GaN. Since is one few reliably identified defects GaN, use Zn-doped GaN as test case widely used HSE06 method defect properties semiconductors. Here, results luminescence measurements from which obtain levels. They are compared theoretically calculated thermodynamic and optical transition levels well zero-phonon line associated acceptor. We...