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.

Segregant-Assisted Growth of SiGe/Si Heterostructures and their Optical Properties

1993 ◽  
Vol 318 ◽  
Author(s):  
Y. Shiraki ◽  
S. Fukatsu ◽  
K. Fujita ◽  
T. Usami
Keyword(s):  
Quantum Wells ◽  
Surface Segregation ◽  
Quantum Confinement Effect ◽  
Growth Front ◽  
Band Edge ◽  
High Quality ◽  
Edge Luminescence ◽  
Band Edge Luminescence ◽  
A New Technique ◽  
Strong Segregation

ABSTRACTA method to realize high quality SiGe/Si heterostructures where surface segregation seriously deteriorates the interface integrity is discussed. After clarifying the mechanism of surface segregation, a new technique, called segre-gant-assisted growth (SAG), where atoms having a strong segregation tendency are introduced at heterointerfaces is proposed and its advantages are demonstrated. Intersubband transition of electrons in the conduction band can be clearly observed even in narrow quantum wells (QWs), and the well width dependence reflecting the square shape potential is obtained in the absorption peak energy. Gas source MBE (GSMBE), which is considered to be quasi-SAG with hydrogen generated at the growth front acting as a segregant, is shown to provide high quality SiGe/Si heterostructures with abrupt interfaces. Highly efficient band edge luminescence is observed in the QWs grown by the SAG method, especially by GSMBE, and the quantum confinement effect is confirmed. Electroluminescent diodes providing band edge luminescence are fabricated by this method, suggesting a high potential for SiGe/Si heterostrucutres in device applications.

High Pressure Study of III-Nitrides and Related Heterostructures

1997 ◽  
Vol 499 ◽  
Author(s):  
W. Shan ◽  
J. W. Ager ◽  
W. Walukiewicz ◽  
E. E. Haller ◽  
B. D. Little ◽  
...  
Keyword(s):  
Diamond Anvil Cell ◽  
Epitaxial Films ◽  
Band Edge ◽  
Near Band Edge ◽  
Pl Spectra ◽  
Edge Luminescence ◽  
Diamond Anvil ◽  
Band Edge Luminescence ◽  
First Time ◽  
High Pressure Study

ABSTRACTWe present results of photoluminescence (PL) studies of GaN, InxGa1-xN and AlxGa1-xN alloys, as well as related thin film heterostructures under hydrostatic pressure using the diamond-anvil-cell technique. The GaN PL spectra are dominated by strong and sharp near-band-edge luminescence associated with annihilations of bound excitons and intrinsic free excitons in the crystals. The spectrally well-resolved emission lines allow us to accurately determine their pressure. The PL spectra of InxGa1-xN and AlxGa1-xN epitaxial films were found to exhibit strong near-band-edge luminescence emissions. By examining the pressure dependence of these spectral features, the pressure coefficients for the PL emissions associated with the direct Γ band gap of InxGa1-xN and AlxGa1-xN were determined for the first time.

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.

Light Emission Properties of GaN-Based Double Heterostructures and Quantum Wells

1995 ◽  
Vol 395 ◽  
Author(s):  
D.A.S. Loeber ◽  
J.M. Redwing ◽  
N.G. Anderson ◽  
M.A. Tischler
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Stimulated Emission ◽  
Pump Light ◽  
Band Edge Emission ◽  
Emission Characteristics ◽  
Nitrogen Laser ◽  
Edge Emission ◽  
Edge Luminescence ◽  
Double Heterostructures

ABSTRACTEdge emission characteristics of optically pumped GaN-AlGaN double heterostructures and quantum wells are examined. The samples, which were grown by metalorganic vapor phase epitaxy, are photoexcited with light from a pulsed nitrogen laser. The pump light is focused to a narrow stripe on the sample surface, oriented perpendicular to a cleaved edge, and the edge luminescence is collected and analyzed. We first compare emission characteristics of highly excited GaN-AlGaN double heterostructures grown simultaneously on SiC and sapphire substrates. Polarization resolved spectral properties of edge luminescence from both structures is studied as a function of pump intensity and excitation stripe length. Characteristics indicative of stimulated emission are observed, particularly in the sample grown on SiC. We then present results demonstrating laser emission from a GaN-AlGaN separate-confinement quantum-well heterostructure. At high pump intensities, band edge emission from the quantum well exhibits five narrow (∼1 Å) modes which are evenly spaced by 10Å to within the resolution of the spectrometer. This represents the first demonstration of laser action in a GaN-based quantum-well structure.

ChemInform Abstract: NEAR BAND-EDGE LUMINESCENCE IN ZINC SELENIDE GROWN FROM GALLIUM SOLUTION

1979 ◽  
Vol 10 (21) ◽  
Author(s):  
B. J. FITZPATRICK ◽  
R. N. BHARGAVA ◽  
S. P. HERKO ◽  
P. M. HARNACK
Keyword(s):  
Zinc Selenide ◽  
Band Edge ◽  
Near Band Edge ◽  
Edge Luminescence ◽  
Band Edge Luminescence

Influence of Substrate Temperature on the Structure and Band Edge Luminescence of ZnO Thin Films

2009 ◽  
Vol 29 (10) ◽  
pp. 2938-2942
Author(s):  
张栋 Zhang Dong ◽  
王长征 Wang Changzheng ◽  
何英 He Ying
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Band Edge ◽  
Zno Thin Films ◽  
Edge Luminescence ◽  
Band Edge Luminescence ◽  
Influence Of Substrate

Luminescence in Si/Strained Si1−xGex Heterostructures

1995 ◽  
Vol 379 ◽  
Author(s):  
J.C. Sturm ◽  
A. St. Amour ◽  
Y. Lacroix ◽  
M.L.W. Thewalt
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Surface Passivation ◽  
Band Edge ◽  
Strained Si ◽  
Edge Luminescence ◽  
Recent Developments ◽  
High Pump ◽  
Band Edge Luminescence ◽  
First Time

ABSTRACTThis paper quickly reviews the structure of band-edge luminescence in Si/strained Si1−xGex heterostructures, and then focusses on two recent developments -- the origin of “deep” sub-bandgap luminescence which is sometimes observed in structures grown by Molecular Beam Epitaxy (MBE) and the understanding of the temperature dependence of the band-edge luminescence (up to room temperature). Strong evidence will be presented that the origin of the deep luminescence is radiation damage, and that generated defects are segregated or trapped in the SilxGex layers. The modelling of the temperature dependence by twocarrier numerical simulation is presented for the first time. The work and experimental data show convincingly that the strength of the luminescence at high temperature is controlled by recombination at the top silicon surface, which in turn can be controlled by surface passivation. At high pump powers and low temperatures, Auger recombination reduces the lifetime in the Si1−xGex layers, and leads to a luminescence vs. temperature which is flat up to 250 K and which is reduced only by a factor of three at room temperature.

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