Controlling barrier height and spectral responsivity of p–i–n based GeSn photodetectors <i>via</i> arsenic incorporation

Nawwar, Mohamed A.; Ghazala, Magdy S. Abo; El-Deen, Lobna M. Sharaf; Anis, Badawi; El-Shaer, Abdelhamid; Elseman, Ahmed Mourtada; Rashad, M.M.; Kashyout, Abd El-Hady B.

doi:10.1039/d3ra00805c

Cited by 5 publications

(2 citation statements)

References 60 publications

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“…Moreover, GeSn alloys show bandgap tunability, a high carrier saturation velocity [ 9 ], high carrier mobility [ 10 ], and a large absorption coefficient [ 11 ]. These unique characteristics have encouraged the development of efficient GeSn-based SWIR and MIR PDs [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Furthermore, a special momentum (k)-space carrier separation scheme enhances the optical performance of the GeSn PDs [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Analysis of GeSn Quantum Dots for Photodetection Applications

Lin,

Ghosh,

Chang

2024

Sensors

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GeSn alloys have recently emerged as complementary metal–oxide–semiconductor (CMOS)-compatible materials for optoelectronic applications. Although various photonic devices based on GeSn thin films have been developed, low-dimensional GeSn quantum structures with improved efficiencies hold great promise for optoelectronic applications. This study theoretically analyses Ge-capped GeSn pyramid quantum dots (QDs) on Ge substrates to explore their potential for such applications. Theoretical models are presented to calculate the effects of the Sn content and the sizes of the GeSn QDs on the strain distributions caused by lattice mismatch, the band structures, transition energies, wavefunctions of confined electrons and holes, and transition probabilities. The bandgap energies of the GeSn QDs decrease with the increasing Sn content, leading to higher band offsets and improved carrier confinement, in addition to electron–hole wavefunction overlap. The GeSn QDs on the Ge substrate provide crucial type–I alignment, but with a limited band offset, thereby decreasing carrier confinement. However, the GeSn QDs on the Ge substrate show a direct bandgap at higher Sn compositions and exhibit a ground-state transition energy of ~0.8 eV, rendering this system suitable for applications in the telecommunication window (1550 nm). These results provide important insights into the practical feasibility of GeSn QD systems for optoelectronic applications.

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Section: Introductionmentioning

confidence: 99%

Theoretical Analysis of GeSn Quantum Dots for Photodetection Applications

Lin,

Ghosh,

Chang

2024

Sensors

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“…Although there have been numerous reports about the dark current densities of GeSn-based PDs [31][32][33][34][35][36][37][38][39][40], very little has been done to clarify the various contributors to the dark-current-density GeSn PDs with different Sn concentrations and the effect of defect density, limiting the optimization of GeSn PDs to achieve uncooled and high-performance MIR photodetection. A few recent experimental studies have shed light on the contributing components of dark currents, such as minority carrier diffusion, Shockley-Read-Hall (SRH) generation-recombination (GR), and trap-assisted tunneling (TAT), providing evidence that the dark current of GeSn PDs is lower with lower defect densities [41][42][43]. This intended to further study the effect of defect density on the PD performance by establishing a theoretical model upon which material and device developers can form realistic expectations in developing GeSn PD architectures for various applications.…”

Section: Introductionmentioning

confidence: 99%

Dark Current Analysis on GeSn p-i-n Photodetectors

Ghosh,

Sun,

Morgan

et al. 2023

Sensors

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Group IV alloys of GeSn have been extensively investigated as a competing material alternative in shortwave-to-mid-infrared photodetectors (PDs). The relatively large defect densities present in GeSn alloys are the major challenge in developing practical devices, owing to the low-temperature growth and lattice mismatch with Si or Ge substrates. In this paper, we comprehensively analyze the impact of defects on the performance of GeSn p-i-n homojunction PDs. We first present our theoretical models to calculate various contributing components of the dark current, including minority carrier diffusion in p- and n-regions, carrier generation–recombination in the active intrinsic region, and the tunneling effect. We then analyze the effect of defect density in the GeSn active region on carrier mobilities, scattering times, and the dark current. A higher defect density increases the dark current, resulting in a reduction in the detectivity of GeSn p-i-n PDs. In addition, at low Sn concentrations, defect-related dark current density is dominant, while the generation dark current becomes dominant at a higher Sn content. These results point to the importance of minimizing defect densities in the GeSn material growth and device processing, particularly for higher Sn compositions necessary to expand the cutoff wavelength to mid- and long-wave infrared regime. Moreover, a comparative study indicates that further improvement of the material quality and optimization of device structure reduces the dark current and thereby increases the detectivity. This study provides more realistic expectations and guidelines for evaluating GeSn p-i-n PDs as a competitor to the III-V- and II-VI-based infrared PDs currently on the commercial market.

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Structure and optical properties of Si thin film improved by metal Cd nanolayers

Rabiea,

AboGhazala,

Zadia

2024

Indian J Phys

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Enhancing the characteristics of amorphous semiconductor thin films is imperative for a multitude of applications. The present study examines the impact of Cd nanolayers deposited on a thin film of amorphous Si. The X-ray test showed that the thin silicon film had less of an amorphous structure after a nanolayer of cadmium was added. There has also been the appearance of new phases, and as the thickness of the Cd nanolayer increases, so does the intensity of these phases. Using a field emission scanning electron microscope, it was seen that nanoparticles were developed and subsequently transformed into clusters as the thickness of the Cd nanolayer grew. The absorbance was maximized at 750 nm and near-infrared region after depositing Cd nanolayers, while transmittance was reduced, especially at 100 nm thicknesses. The energy gap was reduced, with a decrease from 5.1 to 1.8 electron volts (eV). However, an increase in the band tails was also noted, rising from 0.7 to 4.9 eV. An increase in the values of the refractive index (n) and extinction coefficient (k) was observed following the deposition of Cd nanolayers of different thicknesses.

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Controlling barrier height and spectral responsivity of p–i–n based GeSn photodetectors via arsenic incorporation

Abstract: Metal induced crystallization (MIC), strained Ge doped with Sn and As, p–i–n photodetectors, tuned direct transitions, spectral responsivity.

Cited by 5 publications

References 60 publications

Theoretical Analysis of GeSn Quantum Dots for Photodetection Applications

Theoretical Analysis of GeSn Quantum Dots for Photodetection Applications

Dark Current Analysis on GeSn p-i-n Photodetectors

Structure and optical properties of Si thin film improved by metal Cd nanolayers

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