Search

The temperature dependence of electrical properties of (Au/Pd)/Al0.22 Ga0.78N/ GaN Schottky barrier diodes (SBDs) have been deeply analyzed by means of forward Igs (Vgs) measurements over the temperature range of 60-320 K. First results indicate that the barrier height (ϕb), ideality factor (n) and series resistance (Rs) have demonstrated a strongly temperature dependence which suggesting the presence of barrier inhomogeneities at the interface. The effect of spatial inhomogeneity causes fluctuations in the barrier height around an average value. The series resistances obtained from Cheung's function are increasing with increasing temperature. Werner's model consisted in the Schottky contact modeling through inhomogeneities of the barrier which induces the presence of three different average barrier heights each associated with a standard deviation σ. Such abnormal behavior is indeed due to the lateral inhomogeneity of the Schottky barrier, assuming three Gaussian distributions of the barrier height (BH) in three different temperature ranges of 220-320K, 120-200K, and 60-100K, respectively. The (Au/Pd)/ GaN Schottky barrier diode have been shown a Gaussian distribution giving mean s (ϕb) of 0.83, 0.43 and 0.20 eV and standard deviation σ of 139, 74.18 and 35.15 mV for the three temperature regions, respectively. A modified Richardson plot ln (I0/T2) − q2σ2/2k2T2 vs. 1/kT have given ϕb and A* as 0.95 eV and 10.56 A/cm2K2, 0.45 eV and 24.45A/cm2 K2, 0.20 eV and 28.18 A/cm2 K2, respectively. Moreover, the determination of the energy characteristic relating to the transmission probability by tunneling effect E00 made it possible to highlight two conduction modes: conduction by tunnel effect (FE) and a thermionic conduction assisted by field effect (TFE).

Self-assembled InAs/GaAs quantum dots (QD) are extensively studied for their potential application in optoelectronic devices. In this paper, we report the influence of QD growth rate on the optical properties of InAs/GaAs QDs under their exposure to a Nitrogen plasma. The samples under study are grown by molecular beam epitaxy and characterized by photoluminescence spectroscopy (PL). For capped unnitrided QDs, the increase in InAs growth rate is accompanied by an increase in PL emission energy and PL full width at half maximum (FWHM). Under nitridation, it was found that the incorporation of Nitrogen (N) strongly affected the QD emission and showed a significant redshift of the photoluminescence peak emission. In addition, PL FWHM decreases as the growth rate of InAs increases. The temperature dependence of the PL peak energy of the unnitrided and nitrided QDs exhibits a V shape associated to the carrier localization phenomenon induced by the spatially fluctuating potential. This behavior is confirmed by using the localized state ensemble (LSE) theoretical model. In addition, the results suggest that nitridation aims to reduce the size distribution of QDs and leads to their homogenization compared to the case of inhomogeneous distribution in the absence of Nitrogen. These results are a particularly promising method for realizing QD lasers, which require the use of low QD size and high density with minimal size dispersion.

Based on a PC1D (Personal Computer One-Dimensional) simulator device, we have investigated three solar prototypes of gallium arsenide structures labeled as SPI, SPII and SPIII, under AM1.5G condition at one sun irradiation. The PC1D simulation predicts 25% and 25.9% efficiency for n-p and n-i-p GaAs unit solar cells, which is comparable to the National Renewable Energy Laboratory (NREL) measurement (27.6% for 1 cm2 GaAs solar cell). An experimental investigation of 1.9 μm GaInNAs (GINA) through the photoluminescence (PL) technique shows that the investigated quaternary is promising for solar application (Eg = 1.2 eV). Therefore, the i-GINA film sandwiched between n-GaAs and p-GaAs semiconductors is numerically simulated for an area of 1 cm2. The insertion of a GINA layer increases the light-to-electricity yield to 32.4%. The other solar parameters of the cell prototypes are estimated as the following: $$ V_{\rm{oc}}^{{{\rm{SP}}_{\rm{I}} }} = 1.024\;{\hbox{V}} $$ , $$ J_{\rm{sc}}^{{{\rm{SP}}_{\rm{I}} }} = 32.04\;{\hbox{mA}}/{\hbox{cm}}^{2} $$ , FF = 70.7%, $$ V_{\rm{oc}}^{{{\rm{SP}}_{\rm{II}} }} = 1.004\;V $$ , $$ J_{\rm{sc}}^{{{\rm{SP}}_{\rm{II}} }} = 32.11\;{\hbox{mA}}/{\hbox{cm}}^{2} $$ and FF = 66.3% and $$ V_{\rm{oc}}^{{{\rm{SP}}_{\rm{III}} }} = 0.818\;{\hbox{V}} $$ , $$ J_{\rm{sc}}^{{{\rm{SP}}_{\rm{III}} }} = 32.42\;{\hbox{mA}}/{\hbox{cm}}^{2} $$ and FF = 70.2%. An optimization of GINA thickness for a 0.3 μm n-GaAs/4 μm p-GaAs junction consists of a 2.2 μm layer to achieve the highest photovoltaic yield η = 32.6%.

Recently, the technology has evolved towards artificial intelligence world which include IoT (Internet of Things) and IoE (Internet of Everything) as communication between machines or between devices is possible. The development of these systems today requires electronic components capable of generating higher power and frequency levels, which is why new technologies have emerged to meet these needs, GaN HEMT technology. It has attracted a lot of attention for microwave power and high temperature applications. More recently, this technology has become a great interest to the international scientific community for the realization of low noise amplifiers which are the main components of wireless communication systems. In this paper, we modeled an LNA amplifier based on HEMT GaN transistors. This amplifier is unconditionally stable in the X-band (8–12) GHz with a gain of 38 dB, a noise factor does not exceed 2.4 dB and lower input and output reflection coefficients (S11, S22). at -14 dB and − 8 dB respectively. The designed amplifier can be integrated into radar systems, space communications systems and civilian-military radiolocation systems.

We study the optical and vibrational properties of InAlAs alloy films on high-index InP (311)A/B substrate at a wide range of V/III flux ratio (25–125).The crystallinity, vibrational and optical characteristics of InAlAs/InP structures are determined using a combination of photoluminescence (PL) and micro-Raman spectroscopies. Raman studies of InAlAs layer grown on traditional (100)InP substrates show a strong dependence of the optical phonons on V/III molar ratio (Sayari et al. in J Raman Spectrosc 40:1023–1027, 2009). Analysis of PL spectra shows the formation of InAsxP1−x graded layer located at the inverted interface and a broadening of the InAlAs PL band suggests that a clustering effect. Also, a strong dependence of these PL bands on the V/III ratio and substrate polarity is observed and attributed to the clustering effect and to the presence of a strain-induced piezoelectric field. In addition, micro-Raman spectra show a line shape broadening and wave number shift of the Raman peaks for various V/III molar ratios. Furthermore, we discuss the effect laser excitation wavelength on the Raman spectrum. Then, micro-Raman investigations show the presence of an LO mode related to LO-like InAs in InAsP alloy at the inverted interface in our samples. At lower frequencies, disorder-activated longitudinal acoustic phonons are also observed, which considers the presence of potential fluctuations (cluster effect). Finally, by using the modified random-element-iso-displacement theory, we have explained the alloying effect in the InxAl1−xAs layers. A good consistency between calculated and measured InAs and AlAs-like phonon frequencies is obtained. Using the AlAs-like LO phonon frequency shifts, we have calculated the residual strain in the InxAl1−xAs layer. The lower residual strain value is obtained for the (311)A orientation with the lowest V/III ratio and for the (311)B orientation with the largest V/III ratio.

The free buffer InGaAs/InP structure has been elaborated by Metal Organic Vapor Phase Epitaxy (MOVPE). High indium content is chosen to reduce the bandgap energy of the ternary material with direct bandgap to be promoted for Infrared optoelectronic devices. In this work, the temperature dependent photoluminescence (TDPL) analysis of In-rich InxGa1����� xAs (x = 0.65: S1, x = 0.661: S2, and x = 0.667 S3) samples is of the central focus. The S-shaped behavior recorded at low temperature range in the III-V ternary is quantitatively studied herein by Localized State Ensemble (LSE) model. A comparison between the semi-empirical evolution of luminescence versus temperature and our numerical simulation proves the adequacy of computational details, used in LSE model, in well reproducing the S-shape feature. The numerical simulation well matched with PL spectra proving that the localization phenomenon is stronger when increasing the Indium mole fraction. The clustering effect in In-rich structure seems to be beneficial for enhancing the carrier localization within InxGa1����� xAs by localizing carriers from away extended defects that behave probably as non-radiative centers. This is indicative of the utmost importance of localization phenomenon in trapping carriers within localized states instead of dislocations and defects, owing to clustering of indium atoms.

Optical and structural properties in high-x InxGa1-xAs (x > 0.65) samples with varying indium concentration grown on InP (100) substrate are reported. By increasing the indium fraction, it was found by the high-resolution X-ray diffraction (HR-XRD) study that the dislocation density in the InxGa1-xAs epitaxial layer significantly increased, and the surface quality deteriorated remarkably. Photoreflectance (PR) spectra show the presence of Franz-Keldysh Oscillations (FKOs) features above the InxGa1-xAs energy bandgap. The strain-induced electric field is then estimated directly from the FKOs periods. Temperature-dependent photoluminescence (TDPL) measurements from 10 K to 300 K showed carrier locations (S-shape). This abnormal behavior is due to the dislocation density associated with fluctuations in the indium concentration. A quasi-stationary rate equation model for the temperature-dependent luminescence spectra of the localized state material system is proposed to interpret the band gap emission process quantitatively. Low-temperature (10 K) time-resolved PL measurements show the increase of lifetime with increasing the indium concentration. Yet, the addition of only 1.7% of indium concentration results in a strong enhancement of PL lifetime by ~ 80%. All these results reveal a more precise picture of the localization and recombination mechanisms of photogenerated carriers in the InGaAs layer, which could be the crucial factors in controlling the performance of high indium content InGaAs SWIR detector.

The free buffer InGaAs/InP structure has been elaborated by Metal Organic Vapor Phase Epitaxy (MOVPE). High indium content is chosen to reduce the bandgap energy of the ternary material with direct bandgap to be promoted for Infrared optoelectronic devices. In this work, the temperature dependent photoluminescence (TDPL) analysis of In-rich InxGa1− xAs (x = 0.65: S1, x = 0.661: S2, and x = 0.667 S3) samples is of the central focus. The S-shaped behavior recorded at low temperature range in the III-V ternary is quantitatively studied herein by Localized State Ensemble (LSE) model. A comparison between the semi-empirical evolution of luminescence versus temperature and our numerical simulation proves the adequacy of computational details, used in LSE model, in well reproducing the S-shape feature. The numerical simulation well matched with PL spectra proving that the localization phenomenon is stronger when increasing the Indium mole fraction. The clustering effect in In-rich structure seems to be beneficial for enhancing the carrier localization within InxGa1− xAs by localizing carriers from away extended defects that behave probably as non-radiative centers. This is indicative of the utmost importance of localization phenomenon in trapping carriers within localized states instead of dislocations and defects, owing to clustering of indium atoms.

We report self-assembled InAs/GaAs quantum dots (QDs) monolithically grown on a compliant transferable silicon nanomembrane. The transferable silicon nanomembrane with flat continuous crystalline silicon layer formed via in situ porous silicon sintering is considered a low-cost seed for heteroepitaxy of free-standing single-crystalline foils for photovoltaic cells. In this paper, the compliant feature of transferable silicon nanomembrane has been exploited for direct growth of high-quality InAs/GaAs (QDs) by molecular beam epitaxy. Bright 1.3 µm room temperature photoluminescence from InAs/GaAs QDs has been obtained. The excellent structural and optical qualities of the obtained InAs/GaAs quantum dots offer great opportunities for realizing a low-cost and large-scale integration of III–V-based optoelectronic device on silicon.

AlGaN/GaN/Si high electron mobility transistors (HEMTs) developed by molecular beam epitaxy (MBE) are studied with several methods for characterization, the most utilized are direct-current and radio-frequency measurements, to see power and microwave performance of components. The increase in these parameters is not based just with on improvement technological for example, decrease of length gate (Lg) and passivation. For sure, another very important point is to reduce the thickness of barrier while keeping the reduction in the length of gate, in order to reduce the transit time (τ), and consequently access to highest cut-off frequency (FT). For this situation, it’s appears a harmful phenomenon of type “punch-through”, because of the weak confinement of electrons in the channel. In this paper, the main objective is to show how to reduce this effect. Keywords: HEMT GaN, Current-voltage characteristics, RF characteristics, Alloys BGaN, Radio-frequency

InAlAs alloy was grown by MOCVD on an InP (311) substrate with different polarities. Measurements of photoluminescence (PL) and photoreflectance (PR) were performed to study the impact of the V/III flux ratio. It is discovered that the PL line was shifted to a greater energy side with the increasing excitation power density, and no saturation was observed of its related PL intensity. It is a fingerprint of type II transition emission. However, the recombination of the type II interface showed a powerful dependence on AsH3 overpressure and substrate polarity. In fact, we have noted an opposite behavior of type II energy transition shift from A to B polarity substrate in respect to V/III ratio variation. PR signals corresponding to Franz-Keldysh Oscillation (FKO) were observed. The analysis of their period has allowed one to assess the value of the PZ field in the samples. PL-luminescence measurements were performed out as a function of temperature. PL peak energy, PL intensity, and half maximum full width show anomalous behaviors. Indicating the existence of localized carriers, they were ascribed to the energy potential modulation associated with the indium cluster formation and PZ field.

International audience; In-rich InxGa1−xAs epitaxial layers were grown on InP (1 0 0) substrates by a metalorganic vapor phase epitaxy (MOVPE) technique. The effect of Indium (In) composition on the crystalline quality and optical properties are investigated. High resolution X-ray diffraction (HR-XRD) measurement and Raman scattering spectrum are used to evaluate the crystalline quality, the residual strain and dislocation density property. The number of dislocations in the epitaxial layers is found to increase by increasing the Indium content in order to release the stresses due to the epitaxial clamping. Photoluminescence (PL) measurement is used to characterize the optical properties. At 10 K, PL measurements show that the InGaAs band gap redshifts with the indium content. Moreover, the asymmetry at the low-energy side of the PL peak has been attributed to the presence of localized excitons. In all samples, a blue shift of PL peaks is evidenced by increasing the excitation power density, which is in line with the presence of carrier’s localization and non-idealities in this system. Moreover, the temperature-dependence of the PL peak energy displays an unusual red-blue-red shift (S-shaped) behavior when raising the temperature. These observations can be related to the inhomogeneous distribution of indium which gives rise to the appearance of dislocations and other defects which serve as traps for charge carriers. Interestingly, those highly In-content InxGa1−xAs epitaxial layers show PL emission located between 1637 and 1811 nm (depending on In content) and thus might be suitable for in the design of novel heterostructure devices such as short wave infrared (SWIR) detectors.

A cryogenic investigation of the Kink effect with drain-source bias sweeping process during output characteristics is suggested. An exhaustive study of the field effect dependence on the emission rate from hole traps in AlGaN/GaN HEMT transistors has been realized by means of current DLTS spectroscopy (I-DLTS). We have found that the Kink effect was induced by impact ionization of electron trapped in acceptor-like deep levels with activation energies at about 0.85 eV overhead the valence band of the GaN buffer layer. Using I-DLTS method, three holes traps, labeled A, H1, and H5, have been distinguished. The H1 deep level might correspond to the carbon substituting the N site (CN) which is supposed to be the main cause of the Kink effect. The major H5 trap seems to be gallium vacancy complex (VGa–ON). For the hole trap H1, the phonon-assisted tunneling emission is the dominant mechanism for holes to escape from the trapping centers while for the H5 trap their field dependence shows a classical pure tunneling effect.

In this paper, we have investigated the thermally activated carriers transfer mechanism in closely stacked InAs/GaAs quantum dots (QDs) by means of steady-state photoluminescence (PL) and time-resolved photoluminescence measurements. The 10 K PL spectrum exhibits double-emission peaks where the excitation power dependence reveals that these emission peaks are attributed to large and small QD groups. With increasing the sample temperature, an abnormal line-width shrinkage of large QDs (LQDs) is observed. The increase in PL decay lifetime of LQDs versus temperature is nicely explained as the electron and hole wave function overlap between dot layers induced by vertical electronic coupling effect. Using a thermal escape model, the activation energies for PL thermal quenching at high temperatures (above 80K) were derived from fitting the temperature-dependent PL decay lifetime data of LQDs and SQDs. The determined activation energies show that the escape of electron-hole pairs from QDs occurs via transfer channel located below the wetting layer. These results are well reproduced by a rate equation-based model treating the QDs as a localized-state ensemble. Our results emphasize the important role of the vertically stacked InAs/GaAs QDs structures with thin GaAs spacer layer to slow down the carrier PL decay lifetime of the thermal transfer process between QDs. This finding is important for the use of such structures as intermediate band in solar cells.

In this paper, we explore the second harmonic generation (SHG) in a lens-shaped InAs/GaAs quantum core/shell (LSQCS). The three-dimensional Schrodinger equation is given under the framework of the effective mass approximation and it is solved by using the Finite Difference Method (FDM). In this work, we have studied the effects of the structure dimensions, the applied transverse electric field, the hydrostatic pressure and the temperature on the SHG. Obtained results show that the SHG coefficient experiences an obvious red shift and an increase in magnitude with increasing the core radius. Therefore, we note that the SHG experiences a blue shift (red shift) with increasing temperature (pressure). Moreover, both resonant peaks values of the SHG are not a monotonic function of the applied electric field. Thus, SHG reaches its optimized magnitude at a low electric field intensity which is directed along one side of the cross section of the structure under investigation. Finally, at a low electric field intensity, a comparative analysis has shown that the SHG magnitude in LSQCS was 22% higher than that of the uncapped single quantum dot (SQD and a red shift has occurred.

In this paper, we theoretically study the effects of the structural dimensions, pressure (P) and temperature (T) on transition lifetime (τ), on the linear (α(1)), nonlinear (α(3) ) and total α absorption coefficients for Tera-Hertz range (1.2–2.88 THz). The structure under investigation consists of two laterally coupled InAs/GaAs lens-shaped quantum dots (LCQDs) connected to a wetting layer. This structure is analyzed by using the Finite Difference Method (FDM) and the effective mass approximation. The analytical expressions of the transition life time, linear, nonlinear and total absorption coefficients are discussed by using the density matrix formalism. Obtained results show that the total absorption coefficient achieves a maximum value in Tera-Hertz range and the resonant peaks shift toward the lower energies (higher) by increasing the pressure (temperature). Also, the transition lifetime decrease (increase) by increasing the temperature (pressure). As well, the spacer width (between quantum dots) effect is well studied and can be controlled and adjusted. This theoretical study gives a new degree of freedom in describing devices based on laterally coupled QDs and on the intra-band transitions of electrons to achieve desired nonlinear optical properties in Tera-Hertz field.

In the present work, we report on the charge trapping properties of Germanium Nanocrystals (Ge NCs) self assembled on SiO2 thin layer for promising applications in next-generation non volatile memory by the means of Deep Level Transient Spectroscopy (DLTS) and high frequency C-V method. The Ge NCs were grown via dewetting phenomenon at solid state by Ultra-High Vacuum (UHV) annealing and passivated with silicon before SiO2 capping. The role of the surface passivation is to reduce the electrical defect density at the Ge NCs-SiO2 interface. The presence of the Ge NCs in the oxide of the MOS capacitors strongly affects the C-V characteristics and increases the accumulation capacitance, causes a negative flat band voltage (VFB) shift. The DLTS has been used to study the individual Ge NCs as a single point deep level defect in the oxide. DLTS reveals two main features: the first electron traps around 255 K could correspond to dangling bonds at the Si/SiO2 interface and the second, at high-temperature (>300 K) response, could be originated from minority carrier generation in Ge NCs.

A ternary Indium-Aliminium-Arsenic (InAlAs) is grown, by metal organic chemical vapor deposition (MOCVD), on a substrate InP (311) with polarity A and B, doped with Fer (Fe) atomic. Their optical properties have been studied by photoluminescence spectroscopy (PL) in the whole temperature range from 10 to 300 K. At low temperature region, power dependent analysis of the PL intensity reveals a conventional power law with an exponent n close to one, in agreement with the type II nature of the emission. A red shift of the type II transition has been observed from the sample with polarity A to B. The temperature-dependent PL measurements exhibit abnormal behaviors such as an S-shape in PL-peak energy, and an inverted N-shape in the full width at half maximum (FWHM). These atypical behaviors are linked to the exciton localization phenomenon, which it is more pronounced in the structure with polarity A of substrate orientation. Room temperature-PL spectra covers the both emissions of the 1.3 and the 1.55 μm for (311) A and (311) B InP oriented substrates, respectively. Our results indicate that the In0.513Al0.487As/InP (311) A/B is expected to be advantageous for their application in optical telecommunication.

We report the electrical characteristics at room temperature of (Al,Ga)N/GaN high-electron-mobility transistors with different gate lengths Lg ranging from 0.15 to 2 μm. Static measurements demonstrate an increase of leakage current, whereas the maximum drain–source current and maximum transconductance decrease with increase of the gate length. In addition, drain current–voltage measurements for gate voltage Vgs = −3 V reveal a kink effect, which is pronounced for Lg = 0.15, 0.25, and 0.5 μm and is absent for Lg = 1 and 2 μm. Furthermore, a self-heating effect on the drain current is observed at Vgs = 0 V for a short gate length. By means of deep level transient spectroscopy, we detected one hole trap H1, which is considered to be the main cause of the observed kink effect. Also, the effect of gate length on the static output characteristics and the deep level transient spectroscopy results for Al0.25Ga0.75N/GaN high-electron-mobility transistors is also discussed.

In this work, we have theoretically investigated the indium segregation and In/Ga intermixing effects in lens-shaped InxGa1-xAs/GaAs quantum dots coupled to their wetting layer. In the wetting layer, the segregation phenomenon is described by Muraki's et al. model. However, the radial and vertical indium distributions resulting from In/Ga intermixing effect in the quantum dot were taken into account assuming a three-dimensional Gaussian distribution. The results obtained via the Finite Difference Method clearly showed that the introduction of such effects is of a great importance to match the photoluminescence data. The obtained results also indicated that the indium segregation in the wetting layer and the inter-diffusion inside the quantum dots dramatically affected the linear, nonlinear and total absorption coefficients of the strained nanostructure under investigation. Besides, the obtained results showed that the total absorption coefficient achieved an optimum value with a red shift of the resonant energy upon increasing the pressure and a blue shift when increasing the temperature.

Cadmium Selenide nanoparticles (CdSe NPs) deposited on ITO substrates were prepared in aqueous solution by spin-coating method using L -Cysteine as organic stabilizer. The effect of solution temperature (ST) on the morphological and optical properties of CdSe NPs, deposited on ITO substrates was investigated by Atomic force microscopy (AFM), UV–Vis absorption, photoluminescence (PL) and time resolved photoluminescence (TRPL) spectroscopy. Results showed that increasing in the ST up to 70 °C improved the crystalline quality of the CdSe NPs, decreased their band gap energy and enhanced the PL intensity. Higher solution temperature induced a reduction in PL intensity with a blue shift of the emission wavelength, which is attributed to quantum confinement effect. The TRPL measurements showed two PL decay times attributed to radiative recombination processes, and the trapping of carriers at the surface states. After heat treatment of the CdSe NCs solution, the decay components were predominated by the fast decay time (89%) suggesting the good surface passivation of nanocrystals.

International audience; A comparison between dewetting properties of amorphous Ge and GeMn layers on SiO2, followed by a detailed study of magnetic and structural properties of GeMn nanocrystals (NCs), is done by means of several characterization techniques. The formation of three-dimensional Ge and GeMn NCs by solid-state dewetting process was evidenced by transmission electron microscopy. Studying the dewetting morphologies revealed a weak dependence on the Mn content. We show that the size of the dewetted NCs is proportional to the initial film thickness. SQUID measurements of GeMn NCs show the ferromagnetic behavior of Mn5Ge3 phase with Curie temperature at 300 K. Raman spectroscopy was performed for GeMn self-assembled NCs in order to investigate the effects of Mn-doping and the nature of the capping layer on the strain level.

The recombination dynamics in BxGa1-xAs alloys on GaAs (001) grown by metal-organic chemical vapor (MOCVD) are investigated using steady-state photoluminescence and Time-Resolved Photoluminescence (TRPL) measurements in the nanosecond range. The decay time as a function of the emission energy and the geometry of the sample (quantum well, epilayer) and post-growth treatment (annealing) is slower for lower-energy emission. In correlation with a systematic study on the photoluminescence features, we have studied the temperature effect on the decay time of the photogenerated carrier. Depending on the geometry of the sample, the exciton dynamics is assisted by the localization phenomenon in the boron-based ternary alloys. It is shown that, at low temperatures, the transfer is mainly ensured by tunneling through localized states where the recombination process is found to be purely radiative in nature. At intermediate temperatures, a competitive process between radiative and non-radiative recombination takes place. For high temperatures, the transfer is assisted by thermal activation, leading to purely non-radiative recombination. We have shown that the unknown state-of-the-art kinetic parameters of the e stage of carrier relaxation and additional carrier recombination dynamics, divulges the particular role of bandgap inhomogeneity and the below-band gap states for the relaxation dynamics that can contribute to the photogeneration mechanisms in BxGa1-xAs/GaAs alloys. Indeed the research findings of this article will help to gain insight into the preliminary carrier relaxation dynamics in boron-based materials.

In this paper, we present the results of structural and room temperature photoluminescence studies on porous GaAs (π-GaAs) capped with GaAs. The porous structure formation was confirmed by scanning electron microscopy (SEM) and relatively homogeneous pores of diameters as small as 4 nm was grown along B directions. X-ray diffraction (XRD) investigations confirm the high crystal quality of the capping layer and a lattice mismatch of 4% between the two layers was determined. The room temperature photoluminescence (PL) spectrum of porous GaAs recorded during steady-state excitation shows a strong PL covering the red–blue band. Time resolved photoluminescence (PLRT) investigations provide evidence for the existence of PL components with different origins.