Room Temperature Photoluminescence from 4H-SiC Epilayers: Non-Destructive Estimation of In-Grown Stacking Fault Density

Omar, Sabih U.; Song, Hai Zheng; Sudarshan, Tangali S.; Chandrashekhar, M. V. S.

doi:10.4028/www.scientific.net/msf.717-720.399

Cited by 2 publications

(4 citation statements)

References 10 publications

(10 reference statements)

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“…Room temperature PL spectroscopy (at excitation wavelength of 300 nm) measured a peak with emission wavelength at 480 nm (2.58 eV) only on the epilayer with high IGSF density (as shown in Fig. 1) [9]. This PL peak is close to Fujiwara et al's report of 8H-IGSFs (2.56-2.70 eV) [3], but different from Feng et al's report (455 nm, i.e.…”

Section: Resultssupporting

confidence: 49%

In-Grown Stacking Faults in SiC-CVD Using Dichlorosilane and Propane as Precursors

Song

Omar

Rana

et al. 2012

MSF

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In-grown stacking faults (IGSFs) were studied in 4H-SiC homoepitaxial growth from a SiH2Cl2-C3H8-H2 system. Most of the IGSFs, start from the epilayer/substrate interface, and exhibit photoluminescence emission peak at 2.58 eV (480 nm) indicating of 8H polytype. The growth parameters, including growth temperature, growth pressure, growth rate, hydrogen etching, et al., varied around the regular growth condition do not show a significant effect on the IGSF generation. Reactor furniture is identified to be a major reason of IGSF formation, especially when the insulation part of the furnace is not completely isolated from the growth zone. Dusting of insulation material is crucial in the formation of IGSFs. When using graphite felt as the insulation material, the IGSF density in the epilayer can be as high at ~104 cm-2. Improvement of the insulation material by using graphite foil reduces the density to 30-100 cm-2. Further reduction of IGSF density to less than 10 cm-2 is achieved by mild pretreatment of the substrate in molten KOH-NaOH eutectic.

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Section: Resultssupporting

confidence: 49%

In-Grown Stacking Faults in SiC-CVD Using Dichlorosilane and Propane as Precursors

Song

Omar

Rana

et al. 2012

MSF

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“…Secondly, the gain is small in graphene-collector mode, indicating that holes excited across the EG/SiC junction are not efficient in providing a base current. In the PL results, DAP emission was found to scale with boron content [3,4]. This offers a potential route to improvement in the VRR.…”

Section: Introductionmentioning

confidence: 83%

“…The sub-bandgap tail visible in the graphene emitter mode signals can be considered in the context of photoluminescence results on similar 4H-SiC epilayers (without graphene), which showed emission at ~515 nm attributed to DAP recombination [3,4]. This indicates that photons at 444 nm have sufficient energy to excite localized DAP states.…”

Section: Introductionmentioning

confidence: 93%

“…A more homogenous contribution to sub-bandgap photocurrent is expected within the area of the EG contact from the other effects mentioned. Due to the large dopant ioniz ation energies in SiC, DAP states have been shown to lead to luminescence and photoconductivity in the visible region [3,4]. Thermal equilibrium between DAPs and band-edge states could give rise to carriers with a sufficient effective mobility to explain the transistor action.…”

Section: Introductionmentioning

confidence: 99%

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Sub-bandgap response of graphene/SiC Schottky emitter bipolar phototransistor examined by scanning photocurrent microscopy

et al. 2017

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Graphene layers grown epitaxially on SiC substrates are attractive for a variety of sensing and optoelectronic applications because the graphene acts as a transparent, conductive, and chemically responsive layer that is mated to a wide-bandgap semiconductor with large breakdown voltage. Recent advances in control of epitaxial growth and doping of SiC epilayers have increased the range of electronic device architectures that are accessible with this system. In particular, a recently-introduced Schottky-emitter bipolar phototransistor (SEPT) based on an epitaxial graphene (EG) emitter grown on a p-SiC base epilayer has been found to exhibit a maximum common emitter current gain of 113 and a UV responsivity of 7.1 A W−1. The behavior of this device, formed on an n+-SiC substrate that serves as the collector, was attributed to a very large minority carrier injection efficiency at the EG/p-SiC Schottky contact. This large minority carrier injection efficiency is in turn related to the large built-in potential found at a EG/p-SiC Schottky junction. The high performance of this device makes it critically important to analyze the sub bandgap visible response of the device, which provides information on impurity states and polytype inclusions in the crystal. Here, we employ scanning photocurrent microscopy (SPCM) with sub-bandgap light as well as a variety of other techniques to clearly demonstrate a localized response based on the graphene transparent electrode and an approximately 1000-fold difference in responsivity between 365 nm and 444 nm excitation. A stacking fault propagating from the substrate/epilayer interface, assigned as a single layer of the 8H-SiC polytype within the 4H-SiC matrix, is found to locally increase the photocurrent substantially. The discovery of this polytype heterojunction opens the potential for further development of heteropolytype devices based on the SEPT architecture.

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Room Temperature Photoluminescence from 4H-SiC Epilayers: Non-Destructive Estimation of In-Grown Stacking Fault Density

Cited by 2 publications

References 10 publications

In-Grown Stacking Faults in SiC-CVD Using Dichlorosilane and Propane as Precursors

In-Grown Stacking Faults in SiC-CVD Using Dichlorosilane and Propane as Precursors

Sub-bandgap response of graphene/SiC Schottky emitter bipolar phototransistor examined by scanning photocurrent microscopy

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