Modelling surface effects in nano wire optoelectronic devices

Römer, Friedhard; Witzigmann, Bernd

doi:10.1007/s10825-012-0424-9

Cited by 9 publications

(4 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To match the internal quantum efficiency achieved by state-of-the-art GaAs-based planar optoelectronic devices, a high-quality GaAs/AlGaAs heterointerface is required in GaAs/AlGaAs core–shell nanowires to reduce surface recombination velocity (SRV) and obtain long room temperature minority carrier lifetimes (τ mc ). − Due to the high surface-to-volume ratio in nanowires, the electronic properties such as carrier lifetimes and mobility are extremely sensitive to the surface and interface states. Research on planar structures has shown that an almost “surface-effect-free” GaAs epilayer with a SRV of only ∼50 cm/s and microsecond τ mc can be achieved by replacing the free GaAs surface with a GaAs/AlGaAs heterointerface. , However, the longest τ mc in GaAs/AlGaAs core–shell nanowires are still in the nanosecond regime. − Both the growth techniques and the nanowire crystal structure − are reported to influence carrier lifetimes in GaAs/AlGaAs core–shell nanowires.…”

mentioning

confidence: 99%

Enhanced Minority Carrier Lifetimes in GaAs/AlGaAs Core–Shell Nanowires through Shell Growth Optimization

et al. 2013

View full text Add to dashboard Cite

The effects of AlGaAs shell thickness and growth time on the minority carrier lifetime in the GaAs core of GaAs/AlGaAs core-shell nanowires grown by metal-organic chemical vapor deposition are investigated. The carrier lifetime increases with increasing AlGaAs shell thickness up to a certain value as a result of reducing tunneling probability of carriers through the AlGaAs shell, beyond which the carrier lifetime reduces due to the diffusion of Ga-Al and/or impurities across the GaAs/AlGaAs heterointerface. Interdiffusion at the heterointerface is observed directly using high-angle annular dark field scanning transmission electron microscopy. We achieve room temperature minority carrier lifetimes of 1.9 ns by optimizing the shell growth with the intention of reducing the effect of interdiffusion.

show abstract

mentioning

confidence: 99%

Enhanced Minority Carrier Lifetimes in GaAs/AlGaAs Core–Shell Nanowires through Shell Growth Optimization

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The effect of the oxygen impurities has been analyzed in more detail by carrier transport simulations of the SQW structure. The simulation framework has been applied for LED as well as solar cell simulations () and employs a drift/diffusion approach for multiple carrier populations which are separated in the energy space . Electrons and holes are divided into a continuum population and a quantized populations per QW.…”

Section: Oxygen Impurity Effectmentioning

confidence: 99%

Effect of oxygen impurities in semipolar III‐nitride light emitting diodes

Römer

Witzigmann

2016

Physica Status Solidi (a)

Self Cite

View full text Add to dashboard Cite

We investigate the effect of oxygen impurities on the internal quantum efficiency of semipolar III‐nitride light emitting diodes (LED) structures grown along the false(202‾1false) direction by means of carrier transport simulations. For the model calculations, realistic doping and impurity profiles obtained by secondary ion mass spectroscopy are used. We discuss the impact of the oxygen impurity density on the operation of the LED and the interaction of the donor‐type oxygen impurities with the acceptor doping. It is shown that up to a certain oxygen concentration, no major degradation of the LED efficiency occurs and that with increasing oxygen impurity density the LED efficiency becomes more sensitive to variations of the acceptor doping profile. The independent variation of the oxygen concentration revealed that oxygen impurities are most critical in the electron blocking layer and the p‐side barrier.

show abstract

“…The simulation model is based on a combined semi-classical and quantum mechanical approach [16,17]. Carriers are assumed to divide into continuum electrons and holes and a bound electron and hole population for each quantum well (QW).…”

Section: Physical Simulationmentioning

confidence: 99%

Acceptor activation model for III-nitride LEDs

Römer

Witzigmann

2015

J Comput Electron

Self Cite

View full text Add to dashboard Cite

One major contribution to the decay of the internal quantum efficiency (IQE) of InGaN/GaN light emitting diodes (LED) at high current densities is the direct carrier leakage. The direct carrier leakage is mainly caused by electron leakage and is therefore strongly affected by the design of the p-region. In this context we investigate the effect of the acceptor doping on the efficiency. Since acceptor impurities in GaN based materials are subject to a high activation energy we discuss the electronic activation mechanisms as well as activation barrier reduction phenomena. By physics based simulation of a GaN-based LED we demonstrate that the processes reducing the acceptor activation energy affect the IQE and the bias voltage characteristics. We show that by designing the acceptor doping profile the efficiency of GaN-based thin film LEDs may be enhanced.

show abstract

Modelling surface effects in nano wire optoelectronic devices

Cited by 9 publications

References 25 publications

Enhanced Minority Carrier Lifetimes in GaAs/AlGaAs Core–Shell Nanowires through Shell Growth Optimization

Enhanced Minority Carrier Lifetimes in GaAs/AlGaAs Core–Shell Nanowires through Shell Growth Optimization

Effect of oxygen impurities in semipolar III‐nitride light emitting diodes

Acceptor activation model for III-nitride LEDs

Contact Info

Product

Resources

About