Energy relaxation time of hot carriers photoexcited in InGaN

Molecular beam epitaxy-grown In x Ga 1Àx N/GaN samples with indium fraction x ranging between 0.44 and 0.784 were studied by pulsed current-voltage (I-V) measurements at 1.7 K. The drift velocity, electron mobility, and electric-field-dependent power loss per electron were determined from analysis of the data. The drift velocity increased linearly while the electron mobility remained constant with increasing electric field. Power balance equations were used to obtain the power loss per electron as a function of the applied electric field in the range of 0 kV cm À1 to 230 kV cm À1 . The results showed that the power loss per electron increased in the x range of 0.44 to 0.66, then slowly decreased in the x range of 0.66 to 0.784. The results obtained for the dependence of the power loss on the electron temperature are compared with current theoretical models for the power loss in two-dimensional (2D) semiconductors, which include both piezoelectric and deformation potential scattering. For all samples, the energy relaxation of electrons is dominated by acoustic phonon emission via piezoelectric interaction.

show abstract

“…where s E is the electron relaxation time ($1 ps for InGaN 27 ). The power loss versus electron temperature calculated from Eq.…”

Section: Resultsmentioning

confidence: 99%

Power Loss Mechanisms in Indium-Rich InGaN Samples

Tiraş

Mutlu

Balkan

2015

Journal of Elec Materi

View full text Add to dashboard Cite

show abstract

“…Similar TT measurements were used to explore the carrier relaxation in another In x Ga (1-x) N alloy with an extremely lower indium composition (x = 0.05). 62 Since the carrier relaxation time was directly calculated based on the time difference between second and third harmonic generations at different excitation energies, the carrier density was not involved in the study.…”

Section: Nitrides and Their Alloysmentioning

confidence: 99%

“…The occurrence of PBE may be explained by the coupling effect of the high carrier density of 2 × 10 18 cm −3 and relatively large phononic bandgap of InGaN (i.e., Factors I and III are satisfied for PBE). Similar TT measurements were used to explore the carrier relaxation in another In x Ga (1‐x) N alloy with an extremely lower indium composition (x = 0.05) 62 . Since the carrier relaxation time was directly calculated based on the time difference between second and third harmonic generations at different excitation energies, the carrier density was not involved in the study.…”

Section: Pbe Mechanisms In Bulk Semiconductorsmentioning

confidence: 99%

Review of the mechanisms for the phonon bottleneck effect in III–V semiconductors and their application for efficient hot carrier solar cells

Zhang

Conibeer

Liu

et al. 2022

Progress in Photovoltaics

View full text Add to dashboard Cite

The hot carrier solar cell aims to significantly boost the power conversion efficiency through fully utilizing the carrier thermalization energy loss. To realize such ultraefficient solar cells, it requires that the excess energy of excited “hot” carriers is captured for power generation by reducing the rate of, or even preventing, carrier cooling. It has been known that phonon bottleneck effects (PBE) play the most decisive role in reducing the carrier thermalization rate. However, the mechanisms underlying PBE are complex and vary in different material systems and are influenced by many factors such as illumination intensity and carrier density (extrinsic), electronic band structure, and phonon dispersion (intrinsic) and quantum confinement (intrinsic). III–V semiconductors are the most popular photovoltaic materials for ultraefficient thin film solar cells due to their high crystal quality and adjustable electronic band structure. Such features reduce some of the complexity of the study of PBE and hot carrier dynamics. Therefore, it is appropriate to identify the PBE mechanisms in these III–V semiconductors. This manuscript systematically reviews the mechanisms underlying PBE in III–V semiconductors in both bulk and nanostructures. There is a tendency for an enhanced PBE in low‐dimensional III–V semiconductors due to quantum and other confinement effects. Multiple quantum wells seem the most promising material system for hot carrier solar cells.

show abstract

“…Much work has been done to explore this issue in terms of carrier density, strain relaxation, operation temperature and carrier-defect scattering. [6][7][8][9] However, the indium composition effect on ultrafast carrier dynamics in InGaN alloys at room temperature is still not well investigated heretofore. Because the indium-rich clusters attributing to partial phase segregation are widely observed in InGaN alloys.…”

mentioning

confidence: 99%

“…9) Even though the τ effect of these alloys are relatively short, the time that "hot" carriers take to reach room temperature are all longer than 50 ps at least and much longer than those of the In x Ga (1−x) N(i.e., 0 ⩽ x ⩽ 1) alloys in other work. 6,8,31,[35][36][37] It has been know that the hot phonon bottleneck effect could significantly extend the carrier lifetime and be widely observed in low dimensional structure materials. 38) However, it is quite difficult to observe such an effect for further analysis in bulk InGaN alloys.…”

mentioning

confidence: 99%

Investigation on the effect of indium composition on ultrafast carrier dynamics in InGaN alloys

Zhang

Tang

Lin

et al. 2018

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

In this letter, we investigated the effect of indium composition on carrier relaxation mechanisms in InGaN alloys. Four high quality alloys with indium composition from 25% to 75% were fabricated using energetic neutral atomic-beam lithography/epitaxy molecular beam epitaxy. Using subpicosecond resolved photoluminescence at high carrier density, it was found the effective carrier lifetime extends with increasing indium composition. Moreover, the calculated initial carrier temperature also rises with higher indium composition. These results are consistent with the theoretical prediction that a greater phonon bandgap could reduce the carrier cooling rate to a certain extent via hot carrier bottleneck effect.

show abstract

Energy relaxation time of hot carriers photoexcited in InGaN

Cited by 7 publications

References 8 publications

Power Loss Mechanisms in Indium-Rich InGaN Samples

Power Loss Mechanisms in Indium-Rich InGaN Samples

Review of the mechanisms for the phonon bottleneck effect in III–V semiconductors and their application for efficient hot carrier solar cells

Investigation on the effect of indium composition on ultrafast carrier dynamics in InGaN alloys

Contact Info

Product

Resources

About