Broad Band vs Phonon Resolved Luminescence in Si1−xGex/Si Heterostructures Grown by Molecular Beam Epitaxy

1992 ◽  
Vol 281 ◽  
Author(s):  
D. C. Houghton ◽  
N. L. Rowell ◽  
J.-P. Noel ◽  
M. M. Dion ◽  
J. McCaffrey ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Growth Temperature ◽  
Surface Passivation ◽  
Growth Parameters ◽  
Bulk Material ◽  
Substrate Surface ◽  
Broad Band ◽  
Surface Preparation ◽  
Plan View ◽  
Pl Spectra

ABSTRACTSi1−xGex alloys and multilayers synthesized by solid source MBE on Si(100) substrates have been characterized by low temperature photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM). Phonon resolved transitions originating from excitons bound to shallow impurities were observed in addition to a broad band of intense luminescence. PL spectroscopy over the temperature range 2K to 100K has been used to characterize Si1−xGex/Si heterostructures exhibiting both types of PL spectra. Thin alloy layers exhibited phonon-resolved PL spectra, similar to bulk material, but shifted in energy due to strain and hole quantum confinement. In single quantum wells confinement shifts up to ∼200 meV were observed (1.2 nm wells with x = 0.38) and NP linewidths down to 1.37 meV were obtained. However, the broad PL band (peak energy ∼120meV below the strained bandgap) was predominant when the alloy layer thickness was greater than 2 – 10nm, depending on x, growth temperature, and substrate surface preparation. The strength of the broad PL band was correlated with the areal density of strain perturbations (∼109cm−2 per quantum well; local lattice dilation ∼1.5 nm in diameter) observed in plan-view TEM. The role of MBE growth parameters in determining optical properties was investigated by changing growth temperature, substrate preparation procedures and exploring the effect of surface passivation in a hydrogen ambient. In addition, post growth anneals at temperatures in the range 700°C to 1 100°C were carried out, where interdiffusion removes interfacial asperities and the broad luminescence band decays to zero intensity.

SiGe/Si Quantum Wells by MBE : A Photoluminesence Study

1993 ◽  
Vol 298 ◽  
Author(s):  
D.C. Houghton ◽  
N.L. Rowell ◽  
J.-P. Noel ◽  
G. Aers ◽  
M. Davies ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Broad Band ◽  
Band Edge ◽  
Geometrical Shape ◽  
Excitation Power Density ◽  
Plan View ◽  
Pl Spectra ◽  
Edge Luminescence ◽  
Band Edge Luminescence

AbstractStrained Sil-xGex quantum wells and multi-quantum wells, synthesized by solid source ebeam evaporated MBE on Si(100) substrates have been studied by low temperature photoluminescence (PL) spectroscopy. Phonon resolved transitions originating from excitons bound to shallow impurities in Sil-xGex layers were observed over the temperature range 2K to 100K and used to characterize Sil-xGex/Si heterostructures. Thin Sil-xGex quantum wells exhibited phonon-resolved PL spectra, similar to bulk material, but shifted in energy due to strain, quantum well width and Ge fraction. In single quantum wells confinement shifts up to ∼200 meV were observed (1.2 nm wells with x = 0.38) and NP linewidths down to 1.37 meV were obtained. The confinement shifts were modeled by hole confinement in Sil-xGex wells. An annealing study was performed to investigate the role of Si-Ge interdiffusion on luminescence. Both the geometrical shape and optical emission of the quantum well were found to significantly change through intermixing. In addition to near edge luminescence a broad band of intense luminescence was obtained from several Sil-xGex/Si heterostructures. Some layers exhibited both types of PL spectra. However, the broad PL band (peak energy ∼120meV below the strained bandgap) was predominant when the alloy layer thickness was greater than 2 - 10nm, depending on x, growth temperature, and substrate surface preparation. The strength of the broad PL band was correlated with the areal density of strain perturbations (∼109cm−2 per quantum well corresponding to a spacing of 300nm in the plane of the well; local lattice dilation ∼ 1.5 nm in diameter) observed in plan-view TEM. The first few wells of MQW exhibited only band edge luminescence as was revealed by etching off the upper MQW periods. In addition, post growth anneals at temperatures in the range 700°C to 1100°C were found to enhance band edge luminescence, while the broad luminescence band decayed to zero intensity. Interdiffusion at these these temperatures has been shown to dramatically change the QW shape and consequently interfacial asperities would be expected to disappear, consequently only shallow phonon resolved luminescence is observed in PL after annealing. The influence of PL measurement parameters such as excitation power density and PL sample temperature on the relative strengths of band edge versus broad band luminescence were also consistent with the presence of exciton traps at sites of reduced bandgap.

LP-MOCVD growth of GaAlN/GaN heterostructures on Silicon Carbide. Application to HEMT's devices.

2003 ◽  
Vol 798 ◽  
Author(s):  
M-A. di Forte Poisson ◽  
M. Magis ◽  
M. Tordjman ◽  
R. Aubry ◽  
M. Peschang ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Physical Properties ◽  
Defect Density ◽  
Growth Parameters ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Layer Growth ◽  
Ex Situ ◽  
Nucleation Layer ◽  
Mocvd Growth

ABSTRACTThis paper reports on the LP-MOCVD growth optimisation of GaAlN/GaN heterostructures grown on Silicon Carbide substrates for HEMT applications, and on the first device performances obtained with these structures. The critical impact of some growth parameters on the physical properties of the GaAlN/GaN epilayers has been identified and studied using High Resolution X-Ray diffraction (HR-XRD), AFM, C-V and sonogauge measurements. The SiC substrate surface preparation (both ex-situ and in-situ) and the nucleation layer growth conditions (growth temperature, thickness, composition and strain) have been found to be key steps of the GaAlN/GaN/SiC growth process. SiC substrates from different suppliers have been evaluated and their influence on the physical properties of the GaAlN/GaN HEMT structures investigated. Static characteristics of the devices such as maximum drain current Idss or pinch-off voltage have been correlated with the nucleation layer composition of the HEMT structure and the defect density of the SiC substrate. First devices measured at 10 GHz using a load pull system exhibited CW output power in excess of 2.8 W/mm for a gate length of 0.5 μm. Under static measurements, we found an Idss around 1 A/mm and a pinch-off voltage of –5 V.

scholarly journals Self-Catalyzed InSb/InAs Quantum Dot Nanowires

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 179
Author(s):  
Omer Arif ◽  
Valentina Zannier ◽  
Francesca Rossi ◽  
Daniele Ercolani ◽  
Fabio Beltram ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Quantum Wells ◽  
Growth Temperature ◽  
Growth Rates ◽  
Radial Growth ◽  
Growth Parameters ◽  
Chemical Beam Epitaxy ◽  
Si Substrates ◽  
Single Defect ◽  
Inas Quantum Dot

The nanowire platform offers great opportunities for improving the quality and range of applications of semiconductor quantum wells and dots. Here, we present the self-catalyzed growth of InAs/InSb/InAs axial heterostructured nanowires with a single defect-free InSb quantum dot, on Si substrates, by chemical beam epitaxy. A systematic variation of the growth parameters for the InAs top segment has been investigated and the resulting nanowire morphology analyzed. We found that the growth temperature strongly influences the axial and radial growth rates of the top InAs segment. As a consequence, we can reduce the InAs shell thickness around the InSb quantum dot by increasing the InAs growth temperature. Moreover, we observed that both axial and radial growth rates are enhanced by the As line pressure as long as the In droplet on the top of the nanowire is preserved. Finally, the time evolution of the diameter along the entire length of the nanowires allowed us to understand that there are two In diffusion paths contributing to the radial InAs growth and that the interplay of these two mechanisms together with the total length of the nanowires determine the final shape of the nanowires. This study provides insights in understanding the growth mechanisms of self-catalyzed InSb/InAs quantum dot nanowires, and our results can be extended also to the growth of other self-catalyzed heterostructured nanowires, providing useful guidelines for the realization of quantum structures with the desired morphology and properties.

scholarly journals Indium-Incorporation with InxGa1-xN Layers on GaN-Microdisks by Plasma-Assisted Molecular Beam Epitaxy

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 308 ◽  
Author(s):  
ChengDa Tsai ◽  
Ikai Lo ◽  
YingChieh Wang ◽  
ChenChi Yang ◽  
HongYi Yang ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Quantum Wells ◽  
Growth Temperature ◽  
Molecular Beam ◽  
Growth Parameters ◽  
Flux Ratio ◽  
Indium Content ◽  
High Indium Content

Indium-incorporation with InxGa1-xN layers on GaN-microdisks has been systematically studied against growth parameters by plasma-assisted molecular beam epitaxy. The indium content (x) of InxGa1-xN layer increased to 44.2% with an In/(In + Ga) flux ratio of up to 0.6 for a growth temperature of 620 °C, and quickly dropped with a flux ratio of 0.8. At a fixed In/(In + Ga) flux ratio of 0.6, we found that the indium content decreased as the growth temperature increased from 600 °C to 720 °C and dropped to zero at 780 °C. By adjusting the growth parameters, we demonstrated an appropriate InxGa1-xN layer as a buffer to grow high-indium-content InxGa1-xN/GaN microdisk quantum wells for micro-LED applications.

In Situ Diagnostics of Vuv Laser Cvd of Semiconductor Interfaces by Ftir Spectroscopy and Spectroscopic Ellipsometry

1995 ◽  
Vol 397 ◽  
Author(s):  
M. Barth ◽  
J. Knobloch ◽  
P. Hess
Keyword(s):  
Film Thickness ◽  
Bulk Material ◽  
Substrate Surface ◽  
Cluster Formation ◽  
Interface Layer ◽  
Native Oxide ◽  
Initial Growth ◽  
Difference Spectra ◽  
Si Substrates

ABSTRACTThe growth of high quality amorphous hydrogenated semiconductor films was explored with different in situ spectroscopic methods. Nucleation of ArF laser-induced CVD of a-Ge:H on different substrates was investigated by real time ellipsometry, whereas the F2 laser (157nm) deposition of a-Si:H was monitored by FTIR transmission spectroscopy. The ellipsometric studies reveal a significant influence of the substrate surface on the nucleation stage, which in fact determines the electronic and mechanical properties of the bulk material. Coalescence of initial clusters occurs at a thickness of 16 Å for atomically smooth hydrogen-terminated c-Si substrates, whereas on native oxide covered c-Si substrates the bulk volume void fractions are not reached until 35 Å film thickness. For the first time we present a series of IR transmission spectra with monolayer resolution of the initial growth of a-Si:H. Hereby the film thickness was measured simultaneously using a quartz crystal microbalance with corresponding sensitivity. The results give evidence for cluster formation with a coalescence radius of about 20 Å. Difference spectra calculated for layers at different depths with definite thickness reveal that the hydrogen-rich interface layer stays at the substrate surface and does not move with the surface of the growing film. The decrease of the Urbach energy switching from native oxide to H-terminated substrates suggests a strong influence of the interface morphology on the bulk material quality.

Broad-Band Superluminescent Light Emitting Diodes Incorporating Quantum Dots in Compositionally Modulated Quantum Wells

2006 ◽  
Vol 45 (4A) ◽  
pp. 2542-2545 ◽  
Author(s):  
S. K. Ray ◽  
K. M. Groom ◽  
H. Y. Liu ◽  
M. Hopkinson ◽  
R. A. Hogg
Keyword(s):  
Quantum Dots ◽  
Quantum Wells ◽  
Light Emitting Diodes ◽  
Broad Band ◽  
Light Emitting

scholarly journals Characterisation of III?V Multilayers Grown by Low-pressure Metal Organic Vapour-phase Epitaxy

1993 ◽  
Vol 46 (3) ◽  
pp. 435
Author(s):  
C Jagadish ◽  
A Clark ◽  
G Li ◽  
CA Larson ◽  
N Hauser ◽  
...  
Keyword(s):  
Gallium Arsenide ◽  
Growth Temperature ◽  
Deep Level ◽  
Growth Parameters ◽  
Low Pressure ◽  
Vapour Phase ◽  
Growth Conditions ◽  
Vapour Phase Epitaxy ◽  
Metal Organic ◽  
Organic Vapour

Undoped and doped layers of gallium arsenide and aluminium gallium arsenide have been grown on gallium arsenide by low-pressure metal organic vapour-phase epitaxy (MOVPE). Delta doping and growth on silicon substrates have also been attempted. Of particular interest in the present study has been the influence of growth parameters, such as growth temperature, group III mole fraction and dopant flow, on the electrical and physical properties of gallium arsenide layers. An increase in growth temperature leads to increased doping efficiency in the case of silicon, whereas the opposite is true in the case of zinc. Deep level transient spectroscopy (DTLS) studies on undoped GaAs layers showed two levels, the expected EL2 level and a carbon-related level. The determination of optimum growth conditions has allowed good quality GaAs and AlGaAs epitaxial layers to be produced for a range of applications.`

Do You Really Expect To Grow Epilayers On That? A Rationale For Growing Epilayers On Roughened Surfaces

2006 ◽  
Vol 911 ◽  
Author(s):  
Joseph John Sumakeris ◽  
Brett A. Hull ◽  
Michael J. O'Loughlin ◽  
S. Ha ◽  
Marek Skowronski ◽  
...  
Keyword(s):  
Basal Plane ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Processing Parameters ◽  
Optimal Process ◽  
Device Structure ◽  
Process Route ◽  
Basal Plane Dislocation ◽  
Vf Drift ◽  
Edge Dislocations

AbstractWe describe surface preparation and epilayer growth techniques that readily reduce the density of Vf drift inducing basal plane dislocations in epilayers to less than 10 cm-2 and permit the fabrication of bipolar SiC devices with very good Vf stability. The optimal process route requires etching the substrate surface prior to epilayer growth to enhance the natural conversion of basal plane dislocations into threading edge dislocations during epilayer growth. The surface of this relatively rough “conversion” epilayer is subsequently repolished prior to growing the device structure. We provide details on processing parameters and potential problems as well as describe devices produced using this low basal plane dislocation growth processes.

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