A5043127832- solar cell performance optimization
- Semiconductor Quantum Structures and Devices
- Chalcogenide Semiconductor Thin Films
- Photonic and Optical Devices
- Semiconductor Lasers and Optical Devices
- Nanowire Synthesis and Applications
- Metal Extraction and Bioleaching
- Quantum Dots Synthesis And Properties
- Perovskite Materials and Applications
- Semiconductor materials and interfaces
- Advancements in Semiconductor Devices and Circuit Design
- Silicon and Solar Cell Technologies
- Minerals Flotation and Separation Techniques
- Mineral Processing and Grinding
- Semiconductor materials and devices
- Surface and Thin Film Phenomena
- Thin-Film Transistor Technologies
- Spacecraft Design and Technology
- Radiation Effects in Electronics
- Iron-based superconductors research
Aero Corporation (United States)
2023-2024
University of Illinois Urbana-Champaign
2018-2024
Urbana University
2021
University of Illinois System
2020
University of Minnesota
2017
III–V/Si epitaxial tandems with a 1.7-eV GaAsP top cell promise stable power conversion efficiencies above the fundamental limit of Si single-junction cells. However, have suffered from limited minority carrier diffusion length in cell, leading to reduced short-circuit current densities (JSC) and efficiencies. While conventional wisdom dictates that dislocation density must be boost efficiency, here, we show heterointerface design growth sequence also play critical roles reducing...
Pyrite $\mathrm{Fe}{\mathrm{S}}_{2}$ has long been recognized as a high potential photovoltaic material, due to its exceptionally optical absorption, low toxicity, and the abundance cost of constituents. Despite suitable band gap (0.95 eV), minority carrier diffusion length (100--1000 nm), short-circuit current density, power conversion efficiencies in $\mathrm{Fe}{\mathrm{S}}_{2}$-based solar cells have never exceeded 3% however, primarily open circuit voltages...
III-V lasers based on self-assembled quantum dots (QDs) have attracted widespread interest due to their unique characteristics, including low threshold current density (Jth), sensitivity backreflections, and resistance threading dislocations. While most work date has focused 1.3 μm InAs/GaAs QDs, InP QDs also aroused in emitting at visible wavelengths. Molecular beam epitaxy (MBE) enables the growth of high-density InP/AlGaInP exact (001)-oriented GaAs substrates but requires a relatively...
Over the past 40+ years, III-V materials have been intensively studied for avalanche photodetectors, driven by applications including optical communications, imaging, quantum information processing, and autonomous vehicle navigation. Unfortunately, impact ionization is a stochastic process that introduces noise, thereby limiting sensitivity achievable bandwidths, leading to intense effort mitigate this noise through identification of different device structures. Exploration these has seen...
Monolithically combining silicon nitride ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">S</mml:mi> mathvariant="normal">i</mml:mi> mathvariant="normal">N</mml:mi> </mml:mrow> mathvariant="normal">x</mml:mi> </mml:msub> </mml:math> ) photonics technology with III-V active devices could open a broad range of on-chip applications spanning wide wavelength <mml:mo>∼</mml:mo>...
We demonstrate a two-step procedure for the growth of relaxed GaP on pseudomorphic GaP/Si templates with threading dislocation density (TDD) 1.0–1.1 × 106 cm−2. In lattice-mismatched epitaxy, suppressed nucleation and unimpeded glide during relaxation are both critical to achieve low TDD. Our process realizes former by initiating thin, temperature (Tgrowth) layer latter subsequent high-Tgrowth layer. optimizing low-Tgrowth thickness, we find trade-off where too little thickness does not...
We compare the performance of front-junction (FJ) and rear-heterojunction (RHJ) 1.9 eV GaInP solar cells grown on Si by molecular beam epitaxy. First, time-resolved photoluminescence showed a minority carrier lifetime 11.7 ns for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -GaInP Si, indicating high tolerance to threading dislocations due low mobility holes. were both GaAs substrates in FJ (...
Quantum dots (QDs) epitaxially grown on Si are promising for monolithic integration of light sources a photonics platform. Unlike quantum well (QW) lasers Si, 1.3 μm InAs QD show similar threshold current to those GaAs owing their better dislocation tolerance. To date, research dislocation-tolerant QDs has exclusively focused materials emitting at telecom wavelengths. In this work, we report visible InP with photoluminescence (PL) intensity counterparts despite high threading density (TDD)....
We show that delta-doping boosts the performance of tunnel junctions (TJs) used as interconnects in III-V multijunction solar cells by orders magnitude. The peak current our baseline TJ design consisting p-GaAs/n-GaAs surrounded <formula><tex>$\text{Ga}_{0.51} \text{In}_{0.49}\text{P}$</tex></formula> clads is improved a factor ∼5 × <formula><tex>$10^5$</tex></formula>. relative benefits are even stronger TJs based on wider-bandgap materials with reduced optical...
We directly show that doping type strongly affects the threading dislocation density (TDD) of relaxed GaP on Si, with n-type having a TDD ∼3.1 × 107 cm−2, nearly 30× higher than both p-type and unintentionally doped at ∼1.1 106 cm−2. Such high is undesirable since n-GaP Si serves as starting point for growth epitaxial III-V/Si multi-junction solar cells. After highlighting additional challenges highly n-doped including increased surface roughness, anisotropic strain relaxation, inhomogeneous...
We investigate the effect of Si random pyramid texturing on 1.7eV/1.1eV GaAs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.77</sub> P xmlns:xlink="http://www.w3.org/1999/xlink">0.23</sub> /Si 2-terminal tandem solar cells (hereafter GaAsP/Si). Due to light trapping effect, rear surface increases short-circuit current density bottom cell by 2.76 mA/cm <sup xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> relative an untextured cell. For...
In this work, we show that delta-doping can dramatically improve the performance of tunnel junctions. As an example, one our delta-doped junctions achieved a peak current 3.59 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , while its structurally identical counterpart without reached just 7.32 mA/cm . Several different junction designs were explored with differing amounts optical absorption, and all showed significant improvement...
We present a systematic photoluminescence (PL) study on the effects of doping and rapid thermal annealing (RTA) conditions n- p-GaInP double-heterostructures (DHs) grown by molecular beam epitaxy (MBE). The steady-state (SSPL) intensity lightly doped both improve significantly after RTA, while in contrast, heavily n-GaInP degrades sharply with RTA. Front-junction (FJ) GaInP cells this emitter were severely damaged as expected. Replacing may help to alleviate degradation lead improved...
We review recent progress in GaAsP/Si tandem cells and present a cell with high total short-circuit current density of 38.2 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Comparing the external quantum efficiency (EQE) this benchmark perovskite/Si reveals that at identical top bandgap, GaAsP exhibits higher or comparable EQE all wavelengths, while GaAsP-filtered Si bottom insufficient light trapping parasitic absorption. Future...
2.1 - 2.2 eV top cells are an essential and challenging part of future high-efficiency multi-junction solar cells. In this work, we report AlGaInP grown by molecular beam epitaxy (MBE) on GaAs. As-grown exhibit strong trap-assisted recombination, resulting in high bandgap-voltage offset (W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</sub> ) values compromised carrier collection. Bringing the space charge region cell closer to front...
We investigated the effect of GaAs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> P xmlns:xlink="http://www.w3.org/1999/xlink">1-y</sub> graded buffer layer design and cell structure on GaAsP solar cells grown GaP/Si templates. Heavy Si doping in increases threading dislocation density (TDD) by 2.7× compared to no doping, while heavy Be has little or TDD. Higher TDD bandgap-voltage offset, but its short-circuit current is more complex....
We present a materials and device study on metamorphic 1.7 eV In <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.63</inf> Ga xmlns:xlink="http://www.w3.org/1999/xlink">0.37</inf> P (MM InGaP) grown by molecular beam epitaxy (MBE). Rapid thermal annealing (RTA) greatly enhanced time-resolved photoluminescence lifetimes (τ xmlns:xlink="http://www.w3.org/1999/xlink">TRPL</inf> ) of both MM p- n-InGaP double heterostructures (DHs), suggesting the...