• Transactions on Electrical and Electronic Materials
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• 제3권1호
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• pp.1-3
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• 2002

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process was performed by pulsed laser deposition (PLD). The p-n junction was formed and showed typical I-V characteristics. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.

• 한국재료학회지
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• 제12권4호
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• pp.304-307
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• 2002

A zinc oxide (ZnO) single crystal was used as a substrate in the hydride vapor-phase epitaxy (HVPE) growth of GaN and the structural and optical properties of GaN layer were characterized by x- ray diffraction, transmission electron microscopy, secondary ion mass spectrometry, and photoluminescence (PL) analysis. Despite a good lattice match and an identical structure, ZnO is not an appropriate substrate for application of HVPE growth of GaN. Thick film could not be grown. The substrate reacted with process gases and Ga, being unstable at high temperatures. The crystallinity of ZnO substrate deteriorated seriously with growth time, and a thin alloy layer formed at the growth interface due to the reaction between ZnO and GaN. The PL from a GaN layer demonstrated the impurity contamination during growth possibly due to the out-diffusion from the substrate.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.17-21
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• 2001

We proposed that concentrations of cartier electron as well as ionized donor defects in nonstoichiometric ZnO are proportional to $P^{-1/2}_{O_2}$, whenever they ionizes singly or doubly, by employing the Fermi-Dirac (FD) statistics for ionization of the native thermal defects $Zn_i$ and $V_o$. The effect of acceptor defect, zinc vacancy $V_{Zn}$made by the Frenkel and Schottky disorder reactions, on carrier concentrations was discussed. By application of the FD statistics law to their ionization while the formation of defects is assumed governed by the mass-action law, the calculation results indicate; 1. ZnO shows n-type conductivity with $N_D>$N_A$ and majority concentration of $n{\propto}\;P^{-1/2}_{O_2}$ in a range of $P_{O_2}$, lower than a critical value. 2. As the concentration of acceptor $V_{Zn}$ increases proportional to $P^{1/2}_{O_{2}}$, ZnO made at extremely high $P_{O_{2}}$, can have p-type conductivity with majority concentration of p ${\propto}\;P^{-1/2}_{O_{2}}$. One may not, however, obtain p-type ZnO if the pressure for $N_{D}<$N_{A}$ is too high.

• 한국세라믹학회지
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• 제23권1호
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• pp.44-50
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• 1986

Si-ZnO n-n heterojunction diodes were prespared by r.f diode sputtering of the sintered ZnO target on n-type Si single crystal wafers and their structures and electrical properties were studied. The films were grown orientedly with the c-axis of crystallites perpendicular to the substrate surface at low r.f. powder and grown to polycrystalline films with random orientation at high r. f. powder. The crystallite size increased with the increasing substrate temperture The oriented texture films only were used to prepare the photovoltaic diodes and these didoes showed the photovoltaic effect veing positive of the ZnO side for the photons in the wavelength range of 380-1450nm. The sign reversal of phootovoltage which is the property os isotype heterojunction was not observed because of the degeneration of the ZnO films. The diode showed the forward rectification when it was biased with the ZnO side positive. The current-voltage characteristics exhibited the thermal-current type relationship J∝exp(qV/nkT) with n=1.23 at the low forward bias voltage and the tunnelling-current type relationship J∝exp($\alpha$V) where $\alpha$ was constant independent of temperature at the high forward bias voltage. The crystallite size of ZnO films were influenced largely on the photovoltaic properties of diodes ; The diodes with the films of the larger crystallites showed the poor photovoltaic properties. This reason may be cosidered that the ZnO films with the large crystallites could not grow to the electrically continuous films because the thickness of films was so thin in this experiment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1989년도 춘계학술대회 논문집
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• pp.66-69
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• 1989

After reviewing previous work done on two piezoelectric thin films(PZT, ZnO), ZnO thin piezofim of 1-3UM is fabricated by sputtering on the different substrates(i. e., P+Si/N-Si, SiO2/P+Si/ N-Si, Al/SiO2/ P+Si/ N+Si). The result shows that ZnO piezofilm on the Al has the best c-axis orientation. One of applications for the ZnO piezofilm as an microvalve to control liquid flow is introduced, and which can be controlled electrically and remotely.

• 한국전기전자재료학회논문지
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• 제30권6호
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• pp.372-375
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• 2017

ZnO thin films were deposited by RF magnetron sputtering and then diffused by using an As source in the ampouletube. Also, the ZnO p-n homojunction was made by using As-doped ZnO thin films, and its properties were analyzed. After the As doping, the surface roughness increased, the crystal quality deteriorated, and the full width at half maximum was increased. The As-doped ZnO thin films showed typical p-type properties, and their resistivity was as low as $2.19{\times}10^{-3}{\Omega}cm$, probably because of the in-diffusion from an external As source and out-diffusion from the GaAs substrate. Also, the ZnO p-n junction displayed the typical rectification properties of a p-n junction. Therefore, the As diffusion method is effective for obtaining ZnO films with p-type properties.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.343-343
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• 2011

ZnO has been introduced as one of the good candidates for next generation opto-electronics. Recently, ZnO is known to be suitable for the transparent electrode in organic solar cells and light emitting devices. The contact with n-type organic material has been studied due to the n-type properties of ZnO. However, the surface of ZnO has shown different electronic property with respect to its surface orientation. Therefore, it is presumed that there are differences in the interfacial electronic structures between organic materials and ZnO with different orientation. Therefore, it is required to classify the interfacial electronic structures according to the surface orientation of ZnO. In this study, we measured the interfacial electronic structures between the ZnO substrate having various orientations and a typical n-type organic material, tris-(8-hydroxyquinoline) aluminum (Alq3). In-situ x-ray and ultraviolet photoelectron spectroscopy measurements revealed the interfacial electronic structures. We found the changes in the electronic structures with respect to the orientation of ZnO substrate and it could be used to improve the contact between ZnO and Alq3.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.87.1-87.1
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• 2012

넓은 밴드갭 (3.37eV)과 높은 엑시톤 결합에너지 (60meV)를 가지는 ZnO 물질은 ultra violet light 센서 및 light emitting diode (LED)의 재료로써 많은 연구가 진행되고 있다. 특히 나노와이어 구조를 이용하여 소자를 만들 경우 양자효과와 1차원적 캐리어 수송경로 효과로 인하여 그 특성을 보다 향상 시킬 수 있다. 나노와이어를 이용한 이종접합 p-n 다이오드를 제작하기 위하여 ZnO와 격자상수가 비슷한 GaN, NiO, CoO와 같은 물질들이 나노구조 접합에 많이 쓰이고 있지만, 격자상수 차이로 인해서 접합부분 캐리어 수송효율이 떨어지는 단점을 가지고 있다. n-type과 p-type ZnO를 만들어 동종 접합을 만들 경우 이러한 문제점을 극복할 수 있지만, 도핑되지 않은 ZnO가 n-type을 특성을 나타내기 때문에 안정적인 p-type ZnO 합성에 대한 연구가 필수적이다. 본 연구에서는 안정적인 p-type ZnO 합성을 위해서 수열합성법을 이용하여 phosphorus (P) 도핑을 하였고, 나노와이어 diode 구조를 만들었다. P 도핑으로 인한 격자상수 변화는 x-ray diffraction (XRD)를 사용하여 확인하였고, x-ray photoelectron spectroscopy (XPS)를 통해 도핑 원소를 분석하였으며, 이때의 recification ratio, turn-on voltage 등의 전기적 특성을 평가하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.322.2-322.2
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• 2014

Lighting emitting diodes of n-ZnO/MQW/p-GaN structure are fabricated and investigated. To realize this LED structure, n-ZnO/MQW/p-GaN are grown by MOCVD. At several bias voltages, blue-green light is emitted from the ZnO mesa edge. However, the emission is restricted near the mesa edge. It is seen that the hole current does not spread well. It is because conductivity of p-GaN is extremely small. The break down voltage of the device is small compared to conventional InGaN/GaN LEDs. It is seen that ZnO columnar grain boundaries act as leakage current paths and non-radiative recombination center.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.282.1-282.1
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• 2014

산소 플라즈마 전처리가 ZnO/Si 박막 및 계면에 미치는 영향과 그것이 n-ZnO/p-Si 이종접합 다이오드의 전기적 특성에 관여하는 상관관계 등을 조사하였다. ZnO 박막을 Si 기판 위에 Sputter법으로 증착하였으며, 양질의 n-ZnO/p-Si 다이오드를 제작하기 위하여 산소 플라즈마를 이용하여 Si 기판의 표면을 전처리하는 기법을 선택하였다. 산소 플라즈마에 의해 전처리된 시편의 경우, (002) ZnO 보다 (101) ZnO가 더 우세하게 성장되었으며, (101) ZnO의 완화된 c-축 배향성 때문에 수평방향으로의 박막 성장이 이루어졌고, 그로 인해 ZnO 박막의 결정립 크기가 상대적으로 증가하는 것이 관측되었다. 이처럼 (101) 방향으로 성장된 ZnO 박막의 경우, 산소결공 등의 자생결함 밀도가 상대적으로 높아져 결국 캐리어 농도의 증가를 야기시켰다. 이러한 산소 플라즈마 전처리 효과는 n-ZnO/p-Si 이종접합 다이오드의 전도 특성과 밀접한 관련이 있으며, 특히 다이오드의 전도 특성을 현저히 개선시키는 것으로 관측되었다.