Enhanced drift velocity of photoelectrons in a semiconductor with ultrafast carrier recombination

Reklaitis, A.; Krotkus, A.; Grigaliūnaitė, G.

doi:10.1088/0268-1242/14/10/311

Cited by 16 publications

(13 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This value is consistent with the slope of the linear portion of transient drift velocity curve obtained from MonteCarlo calculations [18]. The corresponding effective mass for holes is m h = 0.106m 0 .…”

supporting

confidence: 87%

“…When coupled with velocity overshoot phenomenon reported in many photoconductor materials [12,16,17,18,19,20], t tr of majority of carriers is reduced to < 1 ps, i.e., t tr ≤ f −1 . For efficient use of SPPs, it is desirable to have thin (∼10 nm) normal metal lines with subwavelength features distributed throughout the active volume (Fig 1a) in a manner that would collectively enhance the optical field intensity in the vicinity of the metal lines.…”

mentioning

confidence: 93%

“…As t tr < 1 ps for majority of carriers in Fig 3, τ is not a critical factor in determining the performance at THz frequencies. A sharp drop in n tr by a factor of 2 for electrons and a factor of 3 for holes at t tr ≈ t onset is due to the lower estimate of carrier velocities for t tr > t onset resulting from the uniform field qasiballistic distribution function [18] applied to a case where fields are inherently inhomogeneous. Although, the above choice of velocity distribution for quasiballistic motion is consistent with the fact that over a large volume fraction of the absorbing layer the static field is ∼18 kV/cm (not shown), a rigorous calculation should include quasiballistic velocity distribution appropriate for inhomogeneous fields.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Enhancing the photomixing efficiency of optoelectronic devices in the terahertz regime

Pilla

2007

Applied Physics Letters

View full text Add to dashboard Cite

A method to reduce the transit time of majority of carriers in photomixers and photo detectors to < 1 ps is proposed. Enhanced optical fields associated with surface plasmon polaritons, coupled with velocity overshoot phenomenon results in net decrease of transit time of carriers. As an example, model calculations demonstrating > 280× (or ∼2800 and 31.8 µW at 1 and 5 THz respectively) improvement in THz power generation efficiency of a photomixer based on Low Temperature grown GaAs are presented. Due to minimal dependence on the carrier recombination time, it is anticipated that the proposed method paves the way for enhancing the speed and efficiency of photomixers and detectors covering UV to far infrared communications wavelengths (300 to 1600 nm).Recent experimental observation of extraordinary optical transmission through a normal metal film having subwavelength holes[1] has generated intense interest in harnessing the underlying physics for photonic applications. It is widely believed that quasi two-dimensional electromagnetic excitations tightly bound to the metal surface known as Surface Plasmon Polaritons (SPPs) are responsible for the observed near field enhancement of the optical radiation. Exponential decay of field components arising from SPPs (penetrating ∼100, ∼10 nm in dielectric and metal respectively), make them highly attractive for miniature photonic circuits and devices [2]. Currently, several potential applications of SPPs are being explored including wave guiding [3] and near-field microscopy [4]. However, application of SPPs to enhance the speed and efficiency of photo detectors or photomixers has not been attempted due to the complexity of underlying physics and optimal device designs involving complicated dielectric-metal structures.In this letter we propose a simple interdigitated metal structure embedded in a suitable semiconductor material to harness SPPs for improving the speed and efficiency of photomixers and detectors. Such a device can be realized with the existing material growth techniques [5]. As an example, we demonstrate via model calculations, significant (> 280×) improvement in the efficiency of a THz photomixer based on Low Temperature grown GaAs (LT-GaAs). Microwave to THz radiation sources in the 0.1 to 10 THz are being extensively studied for their application in communications, medical imaging, and spectroscopy [6,7,8,9,10]. For many applications-compact, narrow-linewidth, widely tunable continuous wave sources are necessary. In particular, to be used as a local oscillator in communications systems the THz source should produce stable output power > 10 µW [8,11]. Among the various techniques being pursued [6,8,11,12,13] electrical down conversion of optical microwave sources in a suitable photomixer [6,11,12] are appealing due to the easy availability of tunable, narrow-linewidth, and stable solid state lasers. However, until now the output power from these photomixers is limited to < 10 µW in the cru- . When the top and bottom interdigitated structures in (b) are con...

show abstract

supporting

confidence: 87%

mentioning

confidence: 93%

mentioning

confidence: 99%

See 1 more Smart Citation

Enhancing the photomixing efficiency of optoelectronic devices in the terahertz regime

Pilla

2007

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…This effect of electron velocity overshoot [32] is the additional proof of fast electron trapping by QDs. Structures with fewer QD layers would saturate at lower PCA biases, due to the correspondingly lower number of dots and capture sites.…”

Section: Thz Generation In Qd Based Devicesmentioning

confidence: 84%

Quantum dot materials for terahertz generation applications

Leyman

Gorodetsky

Bazieva

et al. 2016

Laser & Photonics Reviews

View full text Add to dashboard Cite

Compact and tunable semiconductor terahertz sources providing direct electrical control, efficient operation at room temperatures and device integration opportunities are of great interest at the present time. One of the most well-established techniques for terahertz generation utilises photoconductive antennas driven by ultrafast pulsed or dualwavelength continuous wave laser systems, though some limitations, such as confined optical wavelength pumping range and thermal breakdown, still exist. The use of quantum dotbased semiconductor materials, having unique carrier dynamics and material properties, can help to overcome limitations and enable efficient optical-to-terahertz signal conversion at room temperatures. Here we discuss the construction of novel and versatile terahertz transceiver systems based on quantum dot semiconductor devices. Configurable, energy-dependent optical and electronic characteristics of quantum-dot-based semiconductors are described, and the resonant response to optical pump wavelength is revealed. Terahertz signal generation and detection at energies that resonantly excite only the implanted quantum dots opens the potential for using compact quantum dot-based semiconductor lasers as pump sources. Proof-ofconcept experiments are demonstrated here that show quantum dot-based samples to have higher optical pump damage thresholds and reduced carrier lifetime with increasing pump power.

show abstract

“…At such short times, the transport of non-thermalized carriers might be expected 8 , 29 due to considerable contribution of the light holes with a large non-degenerate diffusion coefficient. Moreover, ballistic-like spreading of short-living holes dragged by more mobile electrons might be also important for the enhancement of the effective hole diffusion coefficient within the initial few picoseconds after short-pulse excitation, similar to the phenomenon causing the velocity overshoot in low-temperature GaAs 30 .…”

Section: Resultsmentioning

confidence: 99%

Direct Auger recombination and density-dependent hole diffusion in InN

Aleksiejūnas

Podlipskas

Наргелас

et al. 2018

Sci Rep

View full text Add to dashboard Cite

Indium nitride has a good potential for infrared optoelectronics, yet it suffers from fast nonradiative recombination, the true origin of which has not been established with certainty. The diffusion length of free carriers at high densities is not well investigated either. Here, we study carrier recombination and diffusion using the light-induced transient grating technique in InN epilayers grown by pulsed MOCVD on c-plane sapphire. We show that direct Auger recombination governs the lifetime of carriers at densities above ~1018 cm−3. The measured Auger recombination coefficient is (8 ± 1) × 10−29 cm−3. At carrier densities above ~5 × 1019 cm−3, we observe the saturation of Auger recombination rate due to phase space filling. The diffusion coefficient of holes scales linearly with carrier density, increasing from 1 cm2/s in low-doped layers at low excitations and up to ~40 cm2/s at highest carrier densities. The resulting carrier diffusion length remains within 100–300 nm range, which is comparable to the light absorption depth. This feature is required for efficient carrier extraction in bipolar devices, thus suggesting MOCVD-grown InN as the material fit for photovoltaic and photonic applications.

show abstract

Enhanced drift velocity of photoelectrons in a semiconductor with ultrafast carrier recombination

Cited by 16 publications

References 14 publications

Enhancing the photomixing efficiency of optoelectronic devices in the terahertz regime

Enhancing the photomixing efficiency of optoelectronic devices in the terahertz regime

Quantum dot materials for terahertz generation applications

Direct Auger recombination and density-dependent hole diffusion in InN

Contact Info

Product

Resources

About