Temperature Dependence of the Carrier Lifetime in 4H-SiC Epilayers

2010 ◽  
Vol 645-648 ◽  
pp. 203-206 ◽  
Author(s):  
Paul B. Klein ◽  
Rachael L. Myers-Ward ◽  
Kok Keong Lew ◽  
Brenda L. VanMil ◽  
Charles R. Eddy ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Carrier Lifetime ◽  
Surface Recombination ◽  
Surface Trap ◽  
Surface Band ◽  
Lifetime Measurements ◽  
Band Bending ◽  
Deep Defect ◽  
Surface Recombination Rate ◽  
Recombination Processes

The temperature dependence of the carrier lifetime was measured in n-type 4H-SiC epilayers of varying Z1/2 deep defect concentrations and layer thicknesses in order to investigate the recombination processes controlling the carrier lifetime in low- Z1/2 material. The results indicate that in more recently grown layers with lower deep defect concentrations, surface recombination tends to dominate over carrier capture by other bulk defects. Low-injection lifetime measurements were also found to provide a convenient method to assess the surface band bending and surface trap density in samples with a significant surface recombination rate.

scholarly journals Decoupling bulk and surface recombination properties in silicon by depth-dependent carrier lifetime measurements

2021 ◽  
Vol 118 (25) ◽  
pp. 252105
Author(s):  
K. Yokoyama ◽  
J. S. Lord ◽  
J. Miao ◽  
P. Murahari ◽  
A. J. Drew
Keyword(s):  
Carrier Lifetime ◽  
Surface Recombination ◽  
Lifetime Measurements

Minority Carrier Lifetime Measurements in Specific Epitaxial 4H-SiC Layers by the Microwave Photoconductivity Decay

2009 ◽  
Vol 615-617 ◽  
pp. 295-298 ◽  
Author(s):  
Laurent Ottaviani ◽  
Olivier Palais ◽  
Damien Barakel ◽  
Marcel Pasquinelli
Keyword(s):  
Absorption Spectra ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Optical Excitation ◽  
Minority Carrier Lifetime ◽  
Lifetime Measurements ◽  
Recombination Processes ◽  
Photoconductivity Decay ◽  
P Type ◽  
Non Destructive

We report on measurements of the minority carrier lifetime for different epitaxial 4H-SiC layers by using the microwave photoconductivity decay (µ-PCD) method. This is a non-contacting, non-destructive method very useful for the monitoring of recombination processes in semiconductor material. Distinct samples have been analyzed, giving different lifetime values. Transmittance and absorption spectra have also been carried out. The n-type layers, giving rise to a specific absorption peak near 470 nm, are not sensitive to optical excitation for the used wavelengths, as opposite to p-type layers whose lifetime values depend on thickness and doping.

scholarly journals Ultrahigh sensitivity of methylammonium lead tribromide perovskite single crystals to environmental gases

2016 ◽  
Vol 2 (7) ◽  
pp. e1600534 ◽  
Author(s):  
Hong-Hua Fang ◽  
Sampson Adjokatse ◽  
Haotong Wei ◽  
Jie Yang ◽  
Graeme R. Blake ◽  
...  
Keyword(s):  
Single Crystals ◽  
Surface Recombination ◽  
State Density ◽  
Limiting Factors ◽  
Surface Recombination Velocity ◽  
Photoluminescence Intensity ◽  
Trap State ◽  
Surface Trap ◽  
Design And Optimization ◽  
Surface Recombination Rate

One of the limiting factors to high device performance in photovoltaics is the presence of surface traps. Hence, the understanding and control of carrier recombination at the surface of organic-inorganic hybrid perovskite is critical for the design and optimization of devices with this material as the active layer. We demonstrate that the surface recombination rate (or surface trap state density) in methylammonium lead tribromide (MAPbBr3) single crystals can be fully and reversibly controlled by the physisorption of oxygen and water molecules, leading to a modulation of the photoluminescence intensity by over two orders of magnitude. We report an unusually low surface recombination velocity of 4 cm/s (corresponding to a surface trap state density of 108cm−2) in this material, which is the lowest value ever reported for hybrid perovskites. In addition, a consistent modulation of the transport properties in single crystal devices is evidenced. Our findings highlight the importance of environmental conditions on the investigation and fabrication of high-quality, perovskite-based devices and offer a new potential application of these materials to detect oxygen and water vapor.

scholarly journals Электронные процессы в кристаллах CdIn-=SUB=-2-=/SUB=-Te-=SUB=-4-=/SUB=-

2018 ◽  
Vol 52 (8) ◽  
pp. 840
Author(s):  
О.Г. Грушка ◽  
С.М. Чупыра ◽  
С.В. Биличук ◽  
О.А. Парфенюк
Keyword(s):  
Electrical Conductivity ◽  
Charge Carrier ◽  
Carrier Lifetime ◽  
Diffusion Length ◽  
Surface Recombination ◽  
Sample Thickness ◽  
Donor Center ◽  
Surface Recombination Rate ◽  
Photoelectric Properties ◽  
Charge Carrier Lifetime

AbstractThe results of investigations of electrical, optical, and photoelectric properties of CdIn_2Te^4 crystals, which were grown by the Bridgman method are presented. It is shown that electrical conductivity is determined mainly by electrons with the effective mass m _ n = 0.44 m _0 and the mobility 120–140 cm^2/(V s), which weakly depends on temperature. CdIn_2Te_4 behaves as a partially compensated semiconductor with the donor-center ionization energy E _ d = 0.38 eV and the compensation level K = N _ a / N _ d = 0.36. The absorption-coefficient spectra at the energy hν < E _ g = 1.27 eV are subject to the Urbach rule with a typical energy of 18–25 meV. The photoconductivity depends on the sample thickness. The diffusion length, the charge-carrier lifetime, and the surface-recombination rate are determined from the photoconductivity spectra.

scholarly journals Understanding of Molecular Contribution of Quinhydrone/Methanol Organic Passivation for Improved Minority Carrier Lifetime on Nanostructured Silicon Surface

2019 ◽  
Vol 9 (18) ◽  
pp. 3645
Author(s):  
Jea-Young Choi
Keyword(s):  
Carrier Lifetime ◽  
Surface Passivation ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Complex Surface ◽  
Passivation Layer ◽  
Surface Geometry ◽  
Surface Band ◽  
Band Bending ◽  
Passivation Layers

In this report, we present a study of the quinhydrone/methanol (QHY/MeOH) organic passivation technique for a silicon (Si) surface. The roles of p-benzoquinone (BQ) and hydroquinone (HQ), which make up QHY, in controlling the uniformity and coverage of the passivation layer as well as the minority carrier lifetime (τeff) of Si were investigated. The uniformity and coverage of the passivation layer after treatment with diverse mixture ratios of BQ and HQ in MeOH were studied with two different atomic force microscope (AFM) techniques, namely tunneling mode (TUNA) and high-resolution tapping mode AFM (HR-AFM). In addition, the τeff and surface potential voltages (SPV) of passivated surfaces were measured to clarify the relationship between the morphologies of the passivation layers and degrees of surface band bending. The molecular interactions between BQ and HQ in MeOH were also analyzed using Fourier-transform infrared spectroscopy (FT-IR). In our study, we successfully demonstrated the role of each molecule for effective Si surface passivation with BQ working as a passivation agent and HQ contributing as a proton (H+) donator to BQ for accelerating the passivation rate. However, our study also clearly revealed that HQ could also hinder the formation of a conformal passivation layer, which raises an issue for passivation over complex surface geometry, especially a nanostructured surface.

scholarly journals Influence of surface band bending on a narrow band gap semiconductor: Tunneling atomic force studies of graphite with Bernal and rhombohedral stacking orders

2021 ◽  
Vol 5 (4) ◽  
Author(s):  
Regina Ariskina ◽  
Michael Schnedler ◽  
Pablo D. Esquinazi ◽  
Ana Champi ◽  
Markus Stiller ◽  
...  
Keyword(s):  
Band Gap ◽  
Narrow Band ◽  
Surface Band ◽  
Band Bending ◽  
Atomic Force
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