Nonlinear Optical Techniques for Characterization of Wide Bandgap Semiconductor Electronic Properties: III-nitrides, SiC, and Diamonds

2012 ◽  
Vol 1396 ◽  
Author(s):  
Kęstutis Jarašiūnas ◽  
Ramūnas Aleksiejūnas ◽  
Tadas Malinauskas ◽  
Saulius Nargelas ◽  
Patrik Ščajev
Keyword(s):  
Optical Measurement ◽  
Wide Band ◽  
Wide Bandgap ◽  
Electrical Contacts ◽  
Carrier Lifetimes ◽  
Semiconductor Electronic ◽  
Wide Range ◽  
Recombination Processes ◽  
Bulk Gan ◽  
Bandgap Semiconductors

ABSTRACTCombining interdisciplinary fields of nonlinear optics, dynamic holography, and photoelectrical phenomena, we developed the optical measurement technologies for monitoring the spatial and temporal non-equilibrium carrier dynamics in wide bandgap semiconductors at wide range of excitations (1015 to 1020 cm-3) and temperatures (10 to 800 K).We explored advantages of non-resonant optical nonlinearities, based on a short laser pulse induced refractive or absorption index modulation (Δn and Δk) by free excess carriers. This approach, based on a direct correlation between the electrical and optical processes, opened a possibility to analyze dynamics of electrical phenomena in “all-optical” way, i.e. without electrical contacts.Carrier diffusion and recombination processes have been investigated in various wide band gap materials - differently grown GaN, SiC, and diamonds - and their key electrical parameters determined, as carrier lifetime, diffusion coefficient, diffusion length and their dependences on temperature and injected carrier density. The studies provided deeper insight into nonradiative and radiative recombination processes in GaN crystals, revealed diffusion-driven long nonradiative carrier lifetimes in bulk GaN and SiC, disclosed impact of delocalization in InGaN layers, and suggested a trap-assisted Auger recombination in highly-excited InN. Injection and temperature dependent diffusivity revealed a strong contribution of carrier-carrier scattering in diamond and bandgap renormalization in SiC.

Power Electronic Devices and Systems Based on Bulk GaN Substrates

2018 ◽  
Vol 924 ◽  
pp. 799-804 ◽  
Author(s):  
Eric P. Carlson ◽  
Daniel W. Cunningham ◽  
Yan Zhi Xu ◽  
Isik C. Kizilyalli
Keyword(s):  
High Voltage ◽  
Wide Bandgap ◽  
Performance Limits ◽  
Wide Bandgap Semiconductors ◽  
Power Semiconductor ◽  
Power Transistors ◽  
Wide Range ◽  
Potential Applications ◽  
Bulk Gan ◽  
Bandgap Semiconductors

Wide-bandgap power semiconductor devices offer enormous energy efficiency gains in a wide range of potential applications. As silicon-based semiconductors are fast approaching their performance limits for high power requirements, wide-bandgap semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) with their superior electrical properties are likely candidates to replace silicon in the near future. Along with higher blocking voltages wide-bandgap semiconductors offer breakthrough relative circuit performance enabling low losses, high switching frequencies, and high temperature operation. ARPA-E’s SWITCHES program, started in 2014, set out to catalyze the development of vertical GaN devices using innovations in materials and device architectures to achieve three key aggressive targets: 1200V breakdown voltage (BV), 100A single-die diode and transistor current, and a packaged device cost of no more than ȼ10/A. The program is drawing to a close by the end of 2017 and while no individual project has yet to achieve all the targets of the program, they have made tremendous advances and technical breakthroughs in vertical device architecture and materials development. GaN crystals have been grown by the ammonothermal technique and 2-inch GaN wafers have been fabricated from them. Near theoretical, high-voltage (1700-4000V) and high current (up to 400A pulsed) vertical GaN diodes have been demonstrated along with innovative vertical GaN transistor structures capable of high voltage (800-1500V) and low RON (0.36-2.6 mΩ-cm2). The challenge of selective area doping, needed in order to move to higher voltage transistor devices has been identified. Furthermore, a roadmap has been developed that will allow high voltage/current vertical GaN devices to reach ȼ5/A to ȼ7/A, realizing functional cost parity with high voltage silicon power transistors.

On the Progress Made in GaN Vertical Device Technology

2019 ◽  
Vol 28 (01n02) ◽  
pp. 1940010
Author(s):  
Dong Ji ◽  
Srabanti Chowdhury
Keyword(s):  
Silicon Carbide ◽  
Power Electronics ◽  
Wide Bandgap ◽  
Wide Bandgap Semiconductors ◽  
Wide Range ◽  
Higher Power ◽  
Key Driver ◽  
Bandgap Semiconductors ◽  
Device Technology ◽  
Made In

Silicon technology enabled most of the electronics we witness today, including power electronics. However, wide bandgap semiconductors are capable of addressing high-power electronics more efficiently compared to Silicon, where higher power density is a key driver. Among the wide bandgap semiconductors, silicon carbide (SiC) and gallium nitride (GaN) are in the forefront in power electronics. GaN is promising in its vertical device topology. From CAVETs to MOSFETs, GaN has addressed voltage requirements over a wide range. Our current research in GaN offers a promising view of GaN that forms the theme of this article. CAVETs and OGFETs (a type of MOSFET) in GaN are picked to sketch the key achievements made in GaN vertical device over the last decade.

scholarly journals Superinjection of Holes in Homojunction Diodes Based on Wide-Bandgap Semiconductors

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1972 ◽  
Author(s):  
Igor A. Khramtsov ◽  
Dmitry Yu. Fedyanin
Keyword(s):  
High Speed ◽  
Semiconductor Devices ◽  
Data Communication ◽  
Wide Bandgap ◽  
Light Sources ◽  
Wide Bandgap Semiconductors ◽  
Wide Bandgap Semiconductor ◽  
Wide Range ◽  
Bandgap Semiconductors ◽  
P Type

Electrically driven light sources are essential in a wide range of applications, from indication and display technologies to high-speed data communication and quantum information processing. Wide-bandgap semiconductors promise to advance solid-state lighting by delivering novel light sources. However, electrical pumping of these devices is still a challenging problem. Many wide-bandgap semiconductor materials, such as SiC, GaN, AlN, ZnS, and Ga2O3, can be easily n-type doped, but their efficient p-type doping is extremely difficult. The lack of holes due to the high activation energy of acceptors greatly limits the performance and practical applicability of wide-bandgap semiconductor devices. Here, we study a novel effect which allows homojunction semiconductor devices, such as p-i-n diodes, to operate well above the limit imposed by doping of the p-type material. Using a rigorous numerical approach, we show that the density of injected holes can exceed the density of holes in the p-type injection layer by up to four orders of magnitude depending on the semiconductor material, dopant, and temperature, which gives the possibility to significantly overcome the doping problem. We present a clear physical explanation of this unexpected feature of wide-bandgap semiconductor p-i-n diodes and closely examine it in 4H-SiC, 3C-SiC, AlN, and ZnS structures. The predicted effect can be exploited to develop bright-light-emitting devices, especially electrically driven nonclassical light sources based on color centers in SiC, AlN, ZnO, and other wide-bandgap semiconductors.

XUV-induced transient phase gratings for probing ultra-fast carrier generation and recombination processes in wide-bandgap semiconductors

2012 ◽  
Vol 525 (1-2) ◽  
pp. 59-65
Author(s):  
Markus Gabrysch ◽  
Jörg Schwenke ◽  
Tadas Balciunas ◽  
Xinkui He ◽  
Rafal Rakowski ◽  
...  
Keyword(s):  
Wide Bandgap ◽  
Transient Phase ◽  
Carrier Generation ◽  
Wide Bandgap Semiconductors ◽  
Recombination Processes ◽  
Bandgap Semiconductors

IMPACT IONIZATION AND HIGH FIELD EFFECTS IN WIDE BAND GAP SEMICONDUCTORS

2001 ◽  
Vol 11 (02) ◽  
pp. 511-524 ◽  
Author(s):  
M. REIGROTZKI ◽  
J. R. MADUREIRA ◽  
A. KULIGK ◽  
N. FITZER ◽  
R. REDMER ◽  
...  
Keyword(s):  
Electric Fields ◽  
High Field ◽  
Impact Ionization ◽  
Electron Distribution Function ◽  
Wide Band ◽  
Ionization Rate ◽  
Wide Bandgap ◽  
Bandgap Semiconductors ◽  
Impact Ionization Rate ◽  
The Impact

Impact ionization plays a crucial role for electron transport in wide-bandgap semiconductors at high electric fields. Therefore, a realistic band structure has to be used in calculations of the microscopic scattering rate, as well as high field quantum corrections such as the intercollisional field effect. Here we consider both, and evaluate the impact ionization rate for wide-bandgap materials such as ZnS. A pronounced softening of the impact ionization threshold is obtained, as found earlier for materials like Si and GaAs. This field dependent impact ionization rate is included within a full-band ensemble Monte Carlo simulation of high field transport in ZnS. Although the impact ionization rate itself is strongly affected, little effect is observed on measurable quantities such as the impact ionization coefficient or the electron distribution function itself.

UV p-i-n PHOTODIODES MADE ON WIDE BANDGAP SEMICONDUCTORS

2008 ◽  
Vol 22 (05) ◽  
pp. 369-381
Author(s):  
FERDINAND V. GASPARYAN
Keyword(s):  
Room Temperature ◽  
Function Versus ◽  
Wide Band ◽  
Negative Resistance ◽  
Wide Bandgap ◽  
Current Voltage Characteristic ◽  
Wide Band Gap ◽  
Current Voltage ◽  
Wide Band Gap Semiconductors ◽  
Bandgap Semiconductors

In this paper, results of investigations on the static and dynamic characteristics, responsivity, internal noises, detectivity and noise equivalent power of the forward biased p-i-n photodiode made on wide band gap semiconductors operating in double injection regime are presented. Numerical simulations were made for 4H-SiC and GaN . It is shown that forward biased p-i-n photodiodes have high values of responsivity (~ 0.03 A/W for 4H-SiC and ~ 0.15 A/W for GaN ), detectivity (~1011 cm Hz 1/2 W-1 for 4H-SiC and ~ 8×1013 cm Hz 1/2 W-1 for GaN ) and low level of internal noises at room temperature. It is shown also that dynamic negative resistance on the current–voltage characteristic can come into existence and that the reactive part of the impedance is the sign-changed function versus frequency.

scholarly journals Nano-imprinted subwavelength gratings as polarizing beamsplitters

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Julian Wüster ◽  
Yannick Bourgin ◽  
Patrick Feßer ◽  
Arne Behrens ◽  
Stefan Sinzinger
Keyword(s):  
Nanoimprint Lithography ◽  
Optical Measurement ◽  
Design Method ◽  
Optical Systems ◽  
Surface Metrology ◽  
Measurement Systems ◽  
Common Path ◽  
Dielectric Coatings ◽  
Subwavelength Gratings ◽  
Wide Range

AbstractPolarizing beamsplitters have numerous applications in optical systems, such as systems for freeform surface metrology. They are classically manufactured from birefringent materials or with stacks of dielectric coatings. We present a binary subwavelength-structured form-birefringent diffraction grating, which acts as a polarizing beamsplitter for a wide range of incidence angles −30∘…+30∘. We refine the general design method for such hybrid gratings. We furthermore demonstrate the manufacturing steps with Soft-UV-Nanoimprint-Lithography, as well as the experimental verification, that the structure reliably acts as a polarizing beamsplitter. The experimental results show a contrast in efficiency for TE- and TM-polarization of up to 1:18 in the first order, and 34:1 in the zeroth order. The grating potentially enables us to realize integrated compact optical measurement systems, such as common-path interferometers.

scholarly journals Hybrid ZnO/MoS2 Core/Sheath Heterostructures for Photoelectrochemical Water Splitting

Applied Nano ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 148-161
Author(s):  
Katerina Govatsi ◽  
Aspasia Antonelou ◽  
Labrini Sygellou ◽  
Stylianos G. Neophytides ◽  
Spyros N. Yannopoulos
Keyword(s):  
Visible Light ◽  
Wide Band ◽  
Nanowire Arrays ◽  
Maximum Efficiency ◽  
Light Illumination ◽  
Wide Band Gap ◽  
Long Term Stability ◽  
Visible Light Illumination ◽  
Nanowire Surface ◽  
Wide Range

The rational synthesis of semiconducting materials with enhanced photoelectrocatalytic efficiency under visible light illumination is a long-standing issue. ZnO has been systematically explored in this field, as it offers the feasibility to grow a wide range of nanocrystal morphology; however, its wide band gap precludes visible light absorption. We report on a novel method for the controlled growth of semiconductor heterostructures and, in particular, core/sheath ZnO/MoS2 nanowire arrays and the evaluation of their photoelectrochemical efficiency in oxygen evolution reaction. ZnO nanowire arrays, with a narrow distribution of nanowire diameters, were grown on FTO substrates by chemical bath deposition. Layers of Mo metal at various thicknesses were sputtered on the nanowire surface, and the Mo layers were sulfurized at low temperature, providing in a controlled way few layers of MoS2, in the range from one to three monolayers. The heterostructures were characterized by electron microscopy (SEM, TEM) and spectroscopy (XPS, Raman, PL). The photoelectrochemical properties of the heterostructures were found to depend on the thickness of the pre-deposited Mo film, exhibiting maximum efficiency for moderate values of Mo film thickness. Long-term stability, in relation to similar heterostructures in the literature, has been observed.

scholarly journals Efficient wide-bandgap perovskite solar cells enabled by doping a bromine-rich molecule

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rui He ◽  
Tingting Chen ◽  
Zhipeng Xuan ◽  
Tianzhen Guo ◽  
Jincheng Luo ◽  
...  
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
Open Circuit Voltage ◽  
Perovskite Solar Cells ◽  
Wide Bandgap ◽  
Open Circuit ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Tandem Solar Cells ◽  
Carrier Lifetimes

Abstract Wide-bandgap (wide-E g , ∼1.7 eV or higher) perovskite solar cells (PSCs) have attracted extensive attention due to the great potential of fabricating high-performance perovskite-based tandem solar cells via combining with low-bandgap absorbers, which is considered promising to exceed the Shockley–Queisser efficiency limit. However, inverted wide-E g PSCs with a minimized open-circuit voltage (V oc) loss, which are more suitable to prepare all-perovskite tandem devices, are still lacking study. Here, we report a strategy of adding 1,3,5-tris (bromomethyl) benzene (TBB) into wide-E g perovskite absorber to passivate the perovskite film, leading to an enhanced average V oc. Incorporation of TBB prolongs carrier lifetimes in wide-E g perovskite due to reduction of defects in perovskites and makes a better energy level matching between perovskite absorber and electron transport layer. As a result, we achieve the power conversion efficiency of 17.12% for our inverted TBB-doped PSC with an enhanced V oc of 1.19 V, compared with that (16.14%) for the control one (1.14 V).

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