• Title/Summary/Keyword: p and n-type electrical properties

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High Performance GaN-Based Light-Emitting Diodes by Increased Hole Concentration Via Graphene Oxide Sheets

  • Jeong, Hyun;Jeong, Seung Yol;Jeong, Hyun Joon;Park, Doo Jae;Kim, Yong Hwan;Kim, HyoJung;Lee, Geon-Woong;Jeong, Mun Seok
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.244.1-244.1
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    • 2013
  • The p-type GaN which act as a hole injection layer in GaN-based LEDs has fundamental problems. The first one arises from the difficulty in growing a highly doped p-GaN (with a carrier concentration exceeding ~1018 $cm^{-3}$). And the second one is the absence of appropriate metals or conducting oxides having a work function that is larger than that of p-type GaN (7.5 eV). Moreover, the LED efficiency is decreases gradually as the injection current increases (the so-called 'efficiency droop' phenomenon). The efficiency droop phenomenon in InGaN quantum wells (QWs) has been a large obstacle that has hindered high-efficiency operation at high current density. In this study, we introduce the new approaches to improve the light-output power of LEDs by using graphene oxide sheets. Graphene oxide has many functional groups such as the oxygen epoxide, the hydroxyl, and the carboxyl groups. Due to nature of such functional groups, graphene oxide possess a lot of hole carriers. If graphene oxide combine with LED top surface, graphene oxide may supply hole carriers to p-type GaN layer which has relatively low free carrier concentration less than electron concentration in n-type GaN layer. To prove the enhancement factor of graphene oxide coated LEDs, we have investigated electrical and optical properties by using ultra-violet photo-excited spectroscopy, confocal scanning electroluminescence microscopy.

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Effect of Sn Doping on the Thermoelectric Properties of P-Type Mg3Sb2 Synthesized by Controlled Melting, Pulverizing Followed by Vacuum Hot Pressing

  • Rahman, Md. Mahmudur;Kim, Il-Ho;Ur, Soon-Chul
    • Korean Journal of Materials Research
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    • v.32 no.3
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    • pp.132-138
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    • 2022
  • Zintl phase Mg3Sb2 is a promising thermoelectric material in medium to high temperature range due to its low band gap energy and characteristic electron-crystal phonon-glass behavior. P-type Mg3Sb2 has conventionally exhibited lower thermoelectric properties compared to its n-type counterparts, which have poor electrical conductivity. To address these problems, a small amount of Sn doping was considered in this alloy system. P-type Mg3Sb2 was synthesized by controlled melting, pulverizing, and subsequent vacuum hot pressing (VHP) method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate phases and microstructure development during the process. Single phase Mg3Sb2 was successfully formed when 16 at.% of Mg was excessively added to the system. Nominal compositions of Mg3.8Sb2-xSnx (0 ≤ x ≤ 0.008) were considered in this study. Thermoelectric properties were evaluated in terms of Seebeck coefficient, electrical conductivity, and thermal conductivity. A peak ZT value ≈ 0.32 was found for the specimen Mg3.8Sb1.994Sn0.006 at 873 K, showing an improved ZT value compared to intrinsic one. Transport properties were also evaluated and discussed.

Hall-effect properties of single crystal semiconductor P-GaSe dopes with $Er^{3+}$ (Erbium 도핑된 p-GaSe 단결정의 홀 효과 특성)

  • Lee, Woo-Sun;Oh, Guem-Kon;Chung, Young-Ho;Jung, Chang-Soo;Son, Kyeong-Choon;Kim, Nam-Oh
    • Proceedings of the KIEE Conference
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    • 1998.11c
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    • pp.726-728
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    • 1998
  • Optical and electrical properties of GaSe:$Er^{3+}$ single crystals grown by the Bridgeman technique was been investigated by using optical absorption and Hall-effect measurements. The Hall coefficients were measured by using a high impedance electrometer in the temperature range from 360K to 150K. The temperature dependence of hole concentration shows the characteristic of a partially compensated p-type semiconductor. carrier density($N_H$) of GaSe doped with Erbium was measured about $3.25{\times}10^{16}\;[cm^{-3}}$ at temperature 300K, which was high than undoped specimen. Photon energy gap ($E_{gd}$) was measured about 1.7geV.

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Electrical and Optical properties of $Si-SnO_2 $ Heterojunction ($Si-SnO_2 $ Heterojunction의 전기적 광학적 특성)

  • 김화택
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.13 no.2
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    • pp.23-27
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    • 1976
  • $Si{\cdot}SnO_{2}$ heterojunction was prepared by oxidzing at oxygen atmosphere $SnO_{2-X}$ Which made by Flith evaporation of $SnO_{2}$ powder on III surface of p and n type Si single crystals. The energy band Profile of $Si{\cdot}SnO_{2}$ heterojunction was depicted from its physical properties. This heterojunction was very good rectifying junction, very sensitive in spectral response of Photovoltage at from 400nm to 1200nm, and -10$^{18}$sec of time contant. From above properties, this heterojunction was found ps good high speed photovoltaic device and solar cell.

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Trap-related Electrical Properties of GaN MOSFETs Through TCAD Simulation

  • Doh, Seung-Hyun;Hahm, Sung-Ho
    • Journal of Sensor Science and Technology
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    • v.27 no.3
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    • pp.150-155
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    • 2018
  • Three different structures of GaN MOSFETs with trap distributions, trap levels, and densities were simulated, and its results were analyzed. Two of them are Schottky barrier MOSFETs(SB-MOSFETs): one with a p-type GaN body while the other is in the accumulation mode MOSFET with an undoped GaN body and regrown source/drain. The trap levels, distributions and densities were considered based on the measured or calculated properties. For the SB-MOSFET, the interface trap distribution affected the threshold voltage significantly, but had a relatively small influence on the subthreshold swing, while the bulk trap distribution affects the subthreshold swing more.

Functional Designs of Metal oxide for Transparent Electronics

  • Kim, Joondong;Patel, Malkeshkumar;Kim, Hong-Sik;Kim, Hyunki;Yadav, Pankaj;Park, Wanghee;Ban, Dongkyun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.387.1-387.1
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    • 2016
  • Transparent materials are necessary for most photoelectric devices, which allow the light generation from electric energy or vice versa. Metal oxides are usual materials for transparent conductors to have high optical transmittance with good electrical properties. Functional designs may apply in various applications, including solar cells, photodetectors, and transparent heaters. Nanoscale structures are effective to drive the incident light into light-absorbing semiconductor layer to improve solar cell performances. Recently, the new metal oxide materials have inaugurated functional device applications. Nickel oxide (NiO) is the strong p-type metal oxide and has been applied for all transparent metal oxide photodetector by combining with n-type ZnO. The abrupt p-NiO/n-ZnO heterojunction device has a high transmittance of 90% for visible light but absorbs almost entire UV wavelength light to show the record fastest photoresponse time of 24 ms. For other applications, NiO has been applied for solar cells and transparent heaters to induce the enhanced performances due to its optical and electrical benefits. We discuss the high possibility of metal oxides for current and future transparent electronic applications.

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A Study on the Electrical Properties of Amorphous Sb-Bi-Te Thin Films (비정질 Sb-Bi-Te 박막의 전기적 특성에 관한 연구)

  • ;;D. Mangalaraj
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.3
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    • pp.220-226
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    • 2002
  • Amorphous $Sb_{2-x}Bi_xTe_3$ (x = 0.0, 0.5 and 1.0) thin films were prepared by vacuum evaporation. The resistivity of 7he films decreases from 1.4{\times}10^{-2}$ to $8.84{\times}10^{-5}\Omega cm$ and the type of conductivity changes from p to n with the increase of the x value of the films. D.C. conduction studies on these films ate performed at various electric fields in the temperature range of 303-403 K. At low electric fields, two types of conduction mechanisms, i.e. the variable range hopping and the phonon assisted hopping are found to be responsible for the conduction, depending upon the temperature. The activation energy decreases from 0.082 to 0.076 eV in the temperature range of 303-363 K and from 0.47-0.456 eV in the second range of 363-403 K, indicating the shift of the Fermi level towards the conduction band edge and hence the change of the conduction from P to n type with the increase of the Bi concentration. Poole-Frankel emission dominates at high fields. The shape of the potential well of the localized centre is deduced and the mean free path of the charge carriers is also calculated.

Preparation of p-type transparent semiconductor $SrCu_2O_2$ thin film by RF magnetron sputtering (RF 마그네트론 스퍼터링에 의한 p형 투명 반도체 $SrCu_2O_2$ 박막의 제조)

  • Kim, Sei-Ki;Seok, Hye-Won;Lee, Mi-Jae;Choi, Byung-Hyun;Jeong, Won-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.47-47
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    • 2008
  • P-type transparent semiconductor $SrCu_2O_2$ thin films have been prepared by RF sputtering using low-alkali glass for LCD and quartz as substrates. Single phase of $SrCu_2O_2$ powder was obtained by heating a stoichiometric mixture of CuO and $SrCO_3$ at 1223K for 96h under N2 gas flow, and target was fabricated at 1243K for 24h. Room temperature conductivity of the sintered body was about 0.02S/cm, and the activation energy in the temperature range of $-50^{\circ}C$~RT and RT~$150^{\circ}C$ were 0.18eV, 0.07eV, respectively. Effects of deposition pressure and post-annealing temperature on the electrical and optical properties of the obtained thin film have been investigated.

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Electrical Properties of (PbS)$_{1-x}-(CuS)_{x}$ Thin Films by Chemical Bath Deposition (CBD 방법에 의한 (PbS)$_{1-x}-(CuS)_{x}$ 박막의 전기적 특성)

  • 조종래;조정호;김강언;정수태;조상희
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.13-16
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    • 2000
  • (PbS)$_{1-x}$ -(CuS)$_{x}$ thin films(x=0, 0.5, 1) were grown on glass substrates by using a chemical bath deposition method. The molecular ratio of Pb to Cu for the PbS-CuS thin films(x=0.5) was measured about 7:3 by using EDX and XRF. The resistivity of non-annealed (PbS)$_{1-x}$ -(CuS)$_{x}$ thin films was about 10 $\Omega$ . cm. However, after annealing, the resistivity of PbS showed a little change, while PbS-CuS and CuS significantly decreased in the range of 0.002 to 0.005$\Omega$.cm. PbS was p-type and CuS was n-type.-type.

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Electrical Properties of ZnTe-lnSb Heterojunctions (ZnTe-InSb Heterojunction의 전기적 특성)

  • 김화택
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.12 no.4
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    • pp.35-40
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    • 1975
  • The Zn7e-lnSb heterojunctions was prepared by interface alloying technique. The structure of this beterojunction had p-i-n which semi-insulating ZnTe laver at interface of this heterojunction was formed by diffusing In of InSb into ZnTe crystal. The current transport mechanism of this heterojunction was Spacecharge-Limited-Current(SCLC) mechanism by hole at semi-insulating ZnTe layer. The hole wart injected from valence band of p- type SnTe crystal. Orange color electroluminescence was observed at this heterojunction when forward and reversed bias voltage applied.

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