Optical characterization of excess carrier lifetime and surface recombination in 4H/6H–SiC

Galeckas, Augustinas; Linnros, Jan; Frischholz, M.; Grivickas, V.

doi:10.1063/1.1385588

Cited by 63 publications

(33 citation statements)

References 10 publications

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“…The optical generation of charge carriers circumvents complications arising from chemical doping and, in addition, provides the opportunity to measure out-of-equilibrium parameters. a) Electronic mail: rubano@fisica.unina.it So far, the dynamics of photoinduced charge carriers in intrinsic 3C-and 6H-SiC has been studied using pumpprobe experiments [8][9][10] , however, with a time resolution of nanoseconds and at optical probe frequencies, far above the charge-carrier scattering rates that usually lye in the terahertz (THz) frequency range. 12 Deeper insight could be obtained by performing conductivity measurements using THz electromagnetic pulses having picosecond duration.…”

mentioning

confidence: 99%

Terahertz conductivity and ultrafast dynamics of photoinduced charge carriers in intrinsic 3C and 6H silicon carbide

Rubano¹,

Wolf²,

Kampfrath³

2014

Applied Physics Letters

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The terahertz conductivity of photoinduced charge carriers in two common polytypes of silicon carbide, 3C-SiC and 6H-SiC, is studied on picosecond timescales using an optical-pump / THz-probe technique. We find that the conductivity, measured from 0.7 to 3 THz, is well described by the Drude model, and obtain a velocity relaxation time of 75 fs, independent of sample and charge-carrier density. In contrast, the carrier relaxation rates in the two polytypes differ by orders of magnitude: in 6H-and 3C-SiC, recombination proceeds on a time scale of few picoseconds and beyond nanoseconds, respectively.The technological demand for high-power, hightemperature, and high-field electronic devices requires robust base materials. 1 In this respect, silicon carbide (SiC) is one of the most promising candidates owing to its excellent electrical and structural properties. SiC exists in a large number of polytypes that can be all thought of resulting from stacking three types of bilayer structures (A, B and C) in a certain periodic sequence. The most commonly encountered polytypes are 3C-SiC (stacking order ABC) and 6H-SiC (ABCACB), resulting in a zincblende (two atoms per unit cell) and hexagonal structure (twelve atoms per unit cell), respectively. 2 At room temperature, 3C-and 6H-SiC have an an indirect electronic energy gap of 2.36 eV and 3.0 eV, respectively. 2SiC exhibits exceptional properties that are to a large extent related to the Si-C bond, leading to a stronger localization of the charge density and a larger band gap compared to Si. 2,3 For example, the thermal conductivity of 4.9 and 5.0 W/cm K and breakdown electric field of 3.2 and 1.5 MV/cm for 6H-SiC and 3C-SiC, respectively, 4,5 are about 3 to 5 times larger than those of Si. 2 In addition, the various polytypes make SiC an interesting host material for controlling single electron spins. 6 Also, 6H-SiC may serve as suitable starting material for large-scale graphene production. 7 In order to improve the quality and performance of SiC-based devices, knowledge of fundamental parameters such as the mobility of charge carriers is crucial. Moreover, charge transport is also of considerable interest from the perspective of fundamental physics. So far, the carrier mobility has not been measured in the case of intrinsic samples since they are wide band-gap insulators. A possible approach is to create a transient free-carrier population, for instance by exciting the material with a light pulse. The optical generation of charge carriers circumvents complications arising from chemical doping and, in addition, provides the opportunity to measure out-of-equilibrium parameters. a) Electronic mail: rubano@fisica.unina.it So far, the dynamics of photoinduced charge carriers in intrinsic 3C-and 6H-SiC has been studied using pumpprobe experiments 8-10 , however, with a time resolution of nanoseconds and at optical probe frequencies, far above the charge-carrier scattering rates that usually lye in the terahertz (THz) frequency range. 12 Deeper insight could be obtained by per...

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mentioning

confidence: 99%

Terahertz conductivity and ultrafast dynamics of photoinduced charge carriers in intrinsic 3C and 6H silicon carbide

Rubano¹,

Wolf²,

Kampfrath³

2014

Applied Physics Letters

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“…The high carrier concentration at the p + /n -interface will facilitate the perimeter surface recombination at the diode mesa sidewall and trench bottom, where the recombination velocity is believed to be high due to the un-passivated surface after the RIE [136]. The high carrier concentration at the n -/n + interface will promote recombination at the epilayer and substrate interface, where a high recombination velocity is also expected due to high defect densities.…”

Section: Fig 262 the Effective Minority Carrier Lifetimes As A Funcmentioning

confidence: 99%

Development of Process Technologies for High-Performance MOS-Based SiC Power Switching Devices

Cooper¹,

Capano²,

Feldman³

et al. 2007

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“…13, and the software's default parameters for 4H-SiC Auger recombination were used. The top surface of the emitter was described by a surface recombination velocity (SRV) of 1 9 10 5 cm/s, which is a reasonable value expected for a thermally oxidized surface, 14 and the substrate interface of the epilayer had a SRV of 10 cm/s. 15 The lifetime of the epilayer was also a parameter of the simulation.…”

Section: Numerical Simulation Of Photoexcited Carrier Decaymentioning

confidence: 99%

A Comparison of the Microwave Photoconductivity Decay and Open-Circuit Voltage Decay Lifetime Measurement Techniques for Lifetime-Enhanced 4H-SiC Epilayers

Brunt

Agarwal

Burk

et al. 2013

Journal of Elec Materi

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This work compares the optical microwave photoconductivity decay (lPCD) and electrical open-circuit voltage decay (OCVD) techniques for measuring the ambipolar carrier lifetime in 4H-silicon carbide (4H-SiC) epitaxial layers. Lifetime measurements were carried out by fabricating P + /intrinsic/N + (PiN) diodes on 100-lm-thick, 1 9 10 14 cm À3 to 4.5 9 10 14 cm À3 doped N-type 4 H-SiC epilayers, and measuring the lifetime optically using lPCD prior to metallization, then electrically using OCVD after contact deposition. Both as-grown epilayers as well as epilayers with improved lifetime (via thermal oxidation) were measured using both techniques. The observed ambipolar lifetime was improved from 1.4 ls on an unenhanced wafer to 4 ls on a wafer enhanced through the oxidation process as measured by lPCD. Little difference was observed between the lPCD and OCVD measurements on the unenhanced wafer; the ambipolar lifetime on the enhanced wafer measured by OCVD was approximately 5.5 ls, or 1.5 ls higher than the lPCD measurement. Continuous evaluation of the OCVD transient waveform was necessary due to the high lifetime in the enhanced wafer; shunt resistances included to discharge the P + /N junction capacitance were found to damp the OCVD response and yield low values for the measured lifetime. Simulation of the lPCD measurement including various surface recombination conditions yielded a good match to experimentally observed lPCD measurements for high values of the surface recombination velocity. The OCVD lifetime measurement technique is expected to yield measured lifetime values closer to the physical value due to its independence from surface conditions, provided that the experimental conditions are appropriately chosen.

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Optical characterization of excess carrier lifetime and surface recombination in 4H/6H–SiC

Cited by 63 publications

References 10 publications

Terahertz conductivity and ultrafast dynamics of photoinduced charge carriers in intrinsic 3C and 6H silicon carbide

Terahertz conductivity and ultrafast dynamics of photoinduced charge carriers in intrinsic 3C and 6H silicon carbide

Development of Process Technologies for High-Performance MOS-Based SiC Power Switching Devices

A Comparison of the Microwave Photoconductivity Decay and Open-Circuit Voltage Decay Lifetime Measurement Techniques for Lifetime-Enhanced 4H-SiC Epilayers

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