The role of piezoelectric fields in GaN-based quantum wells

In this contribution, we focus on the consequences of the piezoelectric field, which is an inherent consequence of the commonly used wurtzite phase of GaN, on the optical properties of strained GaN-based quantum well structures. We demonstrate that both in GaN/AlGaN and in GaInN/GaN single quantum well structures, the piezoelectric field leads to a Stark-shift of the fundamental optical transitions, which can lead to luminescence emission far below the bulk bandgap. Due to the spatial separation of the electron and hole wavefunctions in such structures, the oscillator strength of these transitions may become extremely small, many orders of magnitude lower than in the field-free case. From specially designed structures, we can even determine the sign of the piezoelectric field and relate it to the polarity of the layers. Under high-excitation conditions, as found in a laser diode, the piezoelectric field is almost completely screened by the injected carriers. As a consequence, the stimulated emission is significantly blue-shifted compared to the photoluminescence, which has sometimes been confused with localization effects.

Download Full-text

Electric Field Distribution in strained p-i-n GaN/InGaN multiple quantum well structures.

MRS Internet Journal of Nitride Semiconductor Research ◽

10.1557/s1092578300000685 ◽

1999 ◽

Vol 4 (1) ◽

Cited By ~ 8

Author(s):

A.N. Cartwright ◽

Paul M. Sweeney ◽

Thomas Prunty ◽

David P. Bour ◽

Michael Kneissl

Keyword(s):

Quantum Well ◽

Electric Field Distribution ◽

Theoretical Calculations ◽

Multiple Quantum Well ◽

Multiple Quantum ◽

Time Resolved ◽

Quantum Well Structures ◽

Piezoelectric Field ◽

Piezoelectric Fields ◽

Time Resolved Photoluminescence

The presence of piezoelectric fields within p-i-n GaN/InGaN multiple quantum well structures is discussed. Time integrated and time-resolved photoluminescence measurements and theoretical calculations of the effect of these fields is presented. Furthermore, a description of how these fields influence the carrier dynamics and a discussion of how the piezoelectric field effects the design of GaN/InGaN devices is presented.

Download Full-text

Role of localized excitons in the stimulated emission in ultra-thin CdSe/ZnSe/ZnSSe single quantum-well structures

Superlattices and Microstructures ◽

10.1006/spmi.1996.0570 ◽

1998 ◽

Vol 23 (6) ◽

pp. 1189-1195 ◽

Cited By ~ 2

Author(s):

Shigeo Yamaguchi ◽

Hitoshi Kurusu ◽

Yoichi Kawakami ◽

Shizuo Fujita ◽

Shigeo Fujita

Keyword(s):

Quantum Well ◽

Stimulated Emission ◽

Single Quantum ◽

Single Quantum Well ◽

Quantum Well Structures ◽

Localized Excitons

Download Full-text

Stimulated Emission from Single- and Multiple-Quantum-Well GaN-AlGaN Separate-Confinement Heterostructures

MRS Proceedings ◽

10.1557/proc-449-1203 ◽

1996 ◽

Vol 449 ◽

Author(s):

D. A. S. Loeber ◽

N. G. Anderson ◽

J. M. Redwing ◽

J. S. Flynn ◽

G. M. Smith ◽

...

Keyword(s):

Quantum Well ◽

Quantum Wells ◽

Optical Pumping ◽

Multiple Quantum Well ◽

Emission Spectra ◽

Stimulated Emission ◽

Emission Characteristics ◽

Multiple Quantum ◽

Photoluminescence Properties ◽

Single Quantum Well

ABSTRACTStimulated emission characteristics are examined for GaN-AlGaN separate-confinement quantum-well heterostructures grown by MOVPE on 4H-SiC substrates. We specifically focus on comparison of structures with different quantum well active region designs. Polarization resolved edge emission spectra and stimulated emission thresholds are obtained under optical pumping using a stripe excitation geometry. Stimulated emission characteristics are studied as a function of the number of quantum wells in the structure, and are correlated with surface photoluminescence properties. We find reduced stimulated emission thresholds and increased surface photoluminescence intensities as the number of quantum wells is reduced, with the best results obtained for a single-quantum-well structure. These results should provide useful information for the design of GaN-based quantum well lasers.

Download Full-text

GaAs–AlGaAs multiple-quantum-well lasers for monolithic integration with optical modulators

Canadian Journal of Physics ◽

10.1139/p91-081 ◽

1991 ◽

Vol 69 (3-4) ◽

pp. 491-496 ◽

Cited By ~ 5

Author(s):

F. Chatenoud ◽

K. M. Dzurko ◽

M. Dion ◽

D. Moss ◽

R. Barber ◽

...

Keyword(s):

Quantum Well ◽

Quantum Wells ◽

Cavity Length ◽

Multiple Quantum Well ◽

Monolithic Integration ◽

Quantum Well Lasers ◽

Multiple Quantum ◽

Optical Modulators ◽

Single Quantum Well ◽

Quantum Well Structures

Calculations of multiple-quantum-well laser threshold current show that a common minimum current value exists for each number of wells, at an appropriate cavity length. This optimum cavity length decreases rapidly with increasing number of wells, for instance from about 300 to 110 μm for one to three wells. Granded-index separate-confinement heterostructure (GRINSCH) lasers with 1–10 quantum wells, grown by molecular beam epitaxy, show consistently low threshold currents that agree well with theoretical predictions. Lasing is achieved at 160 A cm−2 and 4.6 mA for broad-area and ridge waveguide single-quantum-well devices, respectively. The field-dependent electroabsorption of these devices when operating as wave-guide modulators indicates good modulation properties for one and three quantum-well structures, with on:off ratios above 55 at lasing wavelength. The behavior becomes more complex with increasing number of wells. This systematic study of discrete multiple-quantum-well lasers and modulators demonstrates that GRINSCH structures with 1–3 wells are the most suitable for monolithic integration. Design rules for the laser cavity are also presented for numbers of wells ranging from 1 to 10.

Download Full-text

The Influence of Defects and Piezoelectric Fields on the Luminescence from InGaN/GaN Single Quantum Wells

MRS Proceedings ◽

10.1557/proc-639-g6.45 ◽

2000 ◽

Vol 639 ◽

Author(s):

S. J. Henley ◽

D. Cherns

Keyword(s):

Electron Microscope ◽

Quantum Wells ◽

Spatial Resolution ◽

Blue Shift ◽

Single Quantum ◽

Single Quantum Well ◽

Plan View ◽

Transmission Electron ◽

Piezoelectric Field ◽

Piezoelectric Fields

ABSTRACTHigh spatial resolution cathodoluminescence (CL) studies have been carried out on GaN/InGaN/(0001)GaN single quantum well (SQW) structures in a field emission scanning electron microscope at 5kV and temperatures down to 8K. Direct comparison of QW CL maps with transmission electron microscope studies of plan-view samples showed that edge type threading dislocations act as non-radiative recombination centers. Spectra taken from extended areas showed a progressive blue shift in the QW emission from around 460nm at low beam intensities to about 445nm as the beam intensity was increased. This effect which correlated with a decrease in the spatial resolution is interpreted as due to an increase in the diffusion length of carriers in the SQW due to a combination of screening of the piezoelectric field and band filling effects.

Download Full-text

Optical Properties of Pseudomorphic InxGa1−xAs Quantum Wells

MRS Proceedings ◽

10.1557/proc-77-437 ◽

1986 ◽

Vol 77 ◽

Cited By ~ 5

Author(s):

N. G. Anderson ◽

Y. C. Lo ◽

R. M. Kolbas

Keyword(s):

Quantum Well ◽

Quantum Wells ◽

Excitation Intensity ◽

Stimulated Emission ◽

Luminescence Properties ◽

Photoluminescence Spectra ◽

Quantum Well Structures ◽

Single Feature ◽

Increasing Temperature ◽

Confining Layers

ABSTRACTThe luminescence properties of MBE-grown pseudomorphic InxGa1−xAs—GaAs quantum-well structures are examined as a function of photoexcitation intensity and temperature. The structures examined consist of single In0.28Ga0.72As or (isolated) multiple In0.16Ga0.84As pseudomorphic wells sandwiched between thick, unstrained GaAs confining layers. Low-temperature photoluminescence spectra for these samples, which range in quantum-well thickness from 17 Å to 50 Å, consist of a single feature attributable to transitions associated with n = 1 electron and j = 3/2, Mj = 3/2 > - hole states. Spectral widths of these peaks are very narrow (7–11 meV), even for a heavily spike-doped sample (Si, ND ∼ 1018 spike-doped at well center). Emission intensities for the quantum-well structures are studied as a function of excitation intensity over the range 3 × 102 ≤ Pex ≤ 6 x 1O4 W/cm2, and one of the samples (x = 0.16, 50 Å undoped wells) prepared as a laser structure is shown to support stimulated emission at an excitation intensity < 104 W/cm2. The excellent luminescence properties of these structures are shown to degrade rapidly with increasing temperature, with radiative efficiencies dropping more than two orders of magnitude over the temperature range 20K – 180K. One possible explanation for this behavior is proposed.

Download Full-text

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

MRS Proceedings ◽

10.1557/proc-395-949 ◽

1995 ◽

Vol 395 ◽

Cited By ~ 2

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.

Download Full-text

Optical properties of GaBiAs single quantum well structures grown by MBE

Semiconductor Science and Technology ◽

10.1088/0268-1242/30/9/094016 ◽

2015 ◽

Vol 30 (9) ◽

pp. 094016 ◽

Cited By ~ 13

Author(s):

O Donmez ◽

A Erol ◽

M C Arikan ◽

H Makhloufi ◽

A Arnoult ◽

...

Keyword(s):

Optical Properties ◽

Quantum Well ◽

Single Quantum ◽

Single Quantum Well ◽

Quantum Well Structures

Download Full-text

C-V and DLTS Investigations of GaAs/InGaAs/GaAs Strained Quantum Well Structures

MRS Proceedings ◽

10.1557/proc-300-115 ◽

1993 ◽

Vol 300 ◽

Author(s):

S. Subramanian ◽

B. M. Arora ◽

A. K. Srivastava ◽

S. Banerjee ◽

G. Fernandes

Keyword(s):

Quantum Well ◽

Band Offset ◽

Full Width ◽

Single Quantum ◽

Single Quantum Well ◽

Quantum Well Structures ◽

Strained Quantum Well ◽

Good Agreement

ABSTRACTIn this paper we report a modified Kroemer's analysis for the determination of the band offset (ΔEc) of single quantum well (SQW) structures from simple C-V measurements. The experimental carrier profile from an MOVPE grown pseudomorphic GaAs/InGaAs/GaAs strained SQW structure shows a sharp accumulation peak bounded by depletion regions on either side. The full width at half maximum of the accumulation peak is comparable to the width of the quantum well. The value of ΔEC obtained from C-V measurement is in good agreement with the values determined by simulation and photoluminescence measurements. DLTS measurements on our SQW samples do not show any peaks which is contrary to the published reports. We believe that it is necessary to carefully isolate the role of interface states, before assigning a DLTS peak to emission from the quantum well.

Download Full-text