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RISS 인기검색어
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- 저자 : I. Jyothi (검색결과 21 건)
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Siva Pratap Reddy, M.,Rajagopal Reddy, V.,Jyothi, I.,Choi, Chel‐,Jong John Wiley Sons, Ltd. 2011 Surface and interface analysis Vol.43 No.9
<P><B>Abstract</B></P><P>Schottky rectifiers are fabricated on <I>n</I>‐type GaN using Ni/Pd metallization scheme and its characteristics have been investigated by current‐voltage (I‐V), Capacitance‐Voltage (C‐V), X‐Ray Diffraction (XRD) and SIMS measurements as a function of annealing temperature. The calculated Schottky barrier height of the as‐deposited contact was found to be 0.60 eV (I‐V), 0.71 eV (C‐V) with an ideality factor of 1.44. However, the barrier height slightly increases after annealing at 300, 400 and 500 °C. On the basis of the experimental results, a high‐quality Schottky contact with barrier height and ideality factor of 0.81 eV (I‐V), 0.88 eV (C‐V) and 1.13 respectively, can be obtained after annealing at 600 °C for 1 min in a nitrogen atmosphere. Further, after annealing at 700 °C, it is found that the barrier height slightly decreased to 0.74 eV (I‐V) and 0.85 eV (C‐V). From the above observations, one can note that Ni/Pd Schottky contact exhibits excellent electrical properties after a rapid thermal annealing at 600 °C. According to the SIMS and XRD analysis, the formation of gallide phases at the Ni/Pd/<I>n</I>‐GaN interface could be the reason of the barrier height increase at elevated annealing temperatures. The Atomic Force Microscopy (AFM) results show that the overall surface morphology of Ni/Pd Schottky contacts on <I>n</I>‐GaN is fairly smooth. The above observations reveal that Ni/Pd Schottky metallization scheme was a good choice for the fabrication of high‐temperature and high‐power device applications. Copyright © 2010 John Wiley & Sons, Ltd.</P>
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Modified electrical characteristics of Pt/n-type Ge Schottky diode with a pyronine-B interlayer
Jyothi, I.,Janardhanam, V.,Rajagopal Reddy, V.,Choi, C.J. Academic Press 2014 Superlattices and microstructures Vol.75 No.-
The electrical characteristics of a Pt/n-type Ge Schottky diode with a pyronine-B (PYR-B) interlayer prepared by spin coating was investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements. It was observed that the barrier height of Pt/PYR-B/n-type Ge (0.65eV) was higher than that of the conventional Pt/n-type Ge Schottky diode (0.58eV). This is attributed to the fact that the organic interlayer increases the effective barrier height by influencing the space-charge region of Ge. The introduction of the PYR-B interlayer led to a reduction of the interface state density in the Pt Schottky contact to n-type Ge. The electric field dependence of the reverse leakage current revealed that Schottky emission and Poole-Frenkel emission mechanisms dominated the reverse current in the Pt/n-type Ge and Pt/PYR-B/n-type Ge Schottky diodes, respectively.
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Jyothi, I.,Seo, M.W.,Janardhanam, V.,Shim, K.H.,Lee, Y.B.,Ahn, K.S.,Choi, C.J. Elsevier Sequoia 2013 Journal of alloys and compounds Vol.556 No.-
We fabricated Er-silicide (ErSi<SUB>1.7</SUB>) Schottky contacts to strained Si-on-insulator (sSOI) with a strain level of 0.77% and investigated their electrical properties in the temperature range of 225-400K. The Schottky parameters such as the barrier height, ideality factor, and series resistance were found to strongly depend on temperature. Barrier height and ideality factor were found to decrease and increase, respectively, with decreasing temperature. The series resistance gradually increased with decreasing temperature. A discrepancy between the Schottky barrier heights calculated from the forward current-voltage (I-V) characteristics and Norde's method indicated a deviation from the ideal thermionic emission of ErSi<SUB>1.7</SUB>/sSOI Schottky diode. The lateral inhomogeneity of the Schottky barrier and potential fluctuations at the interface between ErSi<SUB>1.7</SUB> and sSOI could be a main cause of the difference between the calculated and theoretical values of the Richardson constant. On the basis of a thermionic emission mechanism with a Gaussian distribution of the barrier heights, temperature dependency of ErSi<SUB>1.7</SUB> Schottky contact to sSOI was explained in terms of the barrier height inhomogeneities at the interface.
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Jyothi, I.,Lee, Hoon-Ki,Janardhanam, V.,Lee, Sung-Nam,Choi, Chel-Jong American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.10
<P>The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of a Ti/p-type strained Si-on-insulator (sSOI) Schottky diode were measured as a function of temperature in the range, 175-375 K. The Schottky barrier parameters of the Ti/p-type sSOI diode, which were interpreted using thermionic emission theory, indicated a strong temperature dependence of the barrier height and ideality factor. The barrier height and ideality factor decreased and increased, respectively, with decreasing temperature, which was attributed to the distribution of barrier heights due to the inhomogeneity at the metal-semiconductor interface. In addition, the discrepancy in the barrier heights obtained from the I-V and C-V techniques confirmed the inhomogeneities in the Schottky barrier. The inhomogeneities in the barrier characterized under the assumption of a Gaussian distribution revealed the existence of a double barrier distribution with a transition occurring at 275 K. The Richardson plot interpreted with the Gaussian distribution approach yielded a Richardson constant of 21.4 Acm(-2)K(-2) in the high temperature region close to the theoretical value of 31.6 Acm(-2)K(-2) for p-type sSOI. The low frequency noise measurements of the Ti/p-type sSOI Schottky diodes in the forward bias exhibited a 1/f(gamma) dependence with gamma ranging from 0.67 to 1.30, indicating the origin of noise due to the fluctuations in the carrier number caused by trapping-detrapping processes in the traps of the depletion region. Furthermore, the current-noise-power spectral density indicated the presence of defect states or traps existing in the depletion region or in the forbidden gap of the sample.</P>
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P. R. Sekhar Reddy,V. Janardhanam,I. Jyothi,Shim-Hoon Yuk,V. Rajagopal Reddy,Jae-Chan Jeong,Sung-Nam Lee,Chel-Jong Choi 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.5
The electrical properties of Ti/p-type InP Schottky diodes with and without polyaniline (PANI) interlayer was investigated using current–voltage (I–V) and capacitance–voltage (C–V) measurements. The barrier height of Ti/p-type InP Schottky diode with PANI interlayer was higher than that of the conventional Ti/p-type InP Schottky diode, implying that the organic interlayer influenced the space-charge region of the Ti/p-type InP Schottky junction. At higher voltages, the current transport was dominated by the trap free space-charge-limited current and trap-filled space-charge-limited current in Ti/p-type InP Schottky diode without and with PANI interlayer, respectively. The domination of trap filled space-charge-limited current in Ti/p-type InP Schottky diode with PANI interlayer could be associated with the traps originated from structural defects prevailing in organic PANI interlayer.
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Janardhanam, V.,Jyothi, I.,Lee, J.H.,Yun, H.J.,Won, J.,Lee, Y.B.,Lee, S.N.,Choi, C.J. Elsevier Sequoia 2017 THIN SOLID FILMS - Vol.632 No.-
The electrical properties of Cu-germanide(Cu<SUB>3</SUB>Ge)/n-type Ge Schottky contacts formed as a result of a solid state reaction between Cu and n-type Ge were investigated as a function of the rapid thermal annealing (RTA) temperature and correlated with its microstructural evolution driven by the RTA process. The variations of the barrier height of Cu<SUB>3</SUB>Ge/n-type Ge Schottky rectifiers caused by the RTA process were determined using current-voltage (I-V) and capacitance-voltage (C-V) methods. The Cu<SUB>3</SUB>Ge film formed after annealing at 400<SUP>o</SUP>C exhibited a relatively uniform surface and interface morphology. This led to the formation of a laterally homogenous Schottky barrier in the Cu<SUB>3</SUB>Ge/n-type Ge Schottky diode, resulting in an improvement of its rectifying I-V behavior. On the other hand, after annealing above 500<SUP>o</SUP>C, the Cu<SUB>3</SUB>Ge film was severely agglomerated without film continuity and eventually evolved into isolated islands at 600<SUP>o</SUP>C. Such structural degradation of Cu<SUB>3</SUB>Ge led to a rapid decrease in the barrier height and an increase in the reverse leakage current of the Cu<SUB>3</SUB>Ge/n-type Ge Schottky diode. The electric field dependence of the reverse current showed that the reverse leakage current in the Cu<SUB>3</SUB>Ge/n-type Ge Schottky diodes was dominated by a Poole-Frenkel emission mechanism, regardless of the RTA temperatures.
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V. Janardhanam,I. Jyothi,Shim-Hoon Yuk,Kyu-Hwan Shim,Kee Young Lim,Chel-Jong Choi,Sung-Nam Lee 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.5
The current transport mechanism in permalloy/n-type Ge Schottky diodes was studied over the temperature range from 200 to 400 K. At temperatures above 250 K, the forward current-voltage (I-V ) characteristics of the diode were ideal and obeyed the thermionic emission theory. Below 250 K, however, the recombination process was found to contribute to current transport. Similarly, in reverse bias, the thermionic emission mechanism appeared to dominate current transport at tem- peratures above 250 K, and the carrier generation mechanism dominated the reverse current below 250 K. A temperature-driven change in the current conduction mechanism from conduction domi- nated by low-barrier-height patches to conduction dominated by high-barrier-height regions suggests inhomogeneity in the Schottky barrier height. The barrier height inhomogeneity led to deviations in the Richardson constant from its theoretical value at lower temperatures. The room-temperature low-frequency noise measurements taken at different forward biases for the permalloy/n-type Ge Schottky diodes showed a 1=f dependence with a tight variation of between 1.20 and 1.31. The current dependence of the noise power spectral density exhibited a 1=f noise behavior, indicating the operation of the permalloy/n-type Ge Schottky diodes in the thermionic emission mode.
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Janardhanam, V.,Jyothi, I.,Lee, J.-H.,Kim, J.-Y.,Reddy, V.R.,Choi, C.-J. JAPAN INSTITUTE OF METALS 2014 MATERIALS TRANSACTIONS Vol.55 No.5
We investigated the electrical characteristics of Au/n-GaN Schottky rectifier incorporating a copper pthalocyanine (CuPc) interlayer using current voltage (I-V), capacitance voltage (C-V) and conductance voltage (G-V) measurements. The barrier height of the Au/CuPc/n-GaN Schottky contact was higher than that of the Au/n-GaN Schottky diode, indicating that the CuPc interlayer influenced the space charge region of the n-GaN layer. The series resistance of Au/CuPc/n-GaN Schottky contact extracted from the C-V and G-V methods was dependent on the frequency. In addition, the series resistance obtained from C V and G V characteristics was comparable to that from Cheung's method at sufficiently high frequencies and in strong accumulation regions. The forward log / log V plot of Au/CuPc/n-GaN Schottky contact exhibited four distinct regions having different slopes, indicating different conduction mechanisms in each region. In particular, at higher forward bias, the trap-filled space-charge-limited current was the dominant conduction mechanism of Au/CuPc/n-GaN Schottky contact, implying that the most of traps were occupied by injected carriers at high injection level.
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Reddy, P.R. Sekhar,Janardhanam, V.,Jyothi, I.,Yuk, Shim-Hoon,Reddy, V. Rajagopal,Jeong, Jae-Chan,Lee, Sung-Nam,Choi, Chel-Jong The Institute of Electronics and Information Engin 2016 Journal of semiconductor technology and science Vol.16 No.5
The electrical properties of Ti/p-type InP Schottky diodes with and without polyaniline (PANI) interlayer was investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements. The barrier height of Ti/p-type InP Schottky diode with PANI interlayer was higher than that of the conventional Ti/p-type InP Schottky diode, implying that the organic interlayer influenced the space-charge region of the Ti/p-type InP Schottky junction. At higher voltages, the current transport was dominated by the trap free space-charge-limited current and trap-filled space-charge-limited current in Ti/p-type InP Schottky diode without and with PANI interlayer, respectively. The domination of trap filled space-charge-limited current in Ti/p-type InP Schottky diode with PANI interlayer could be associated with the traps originated from structural defects prevailing in organic PANI interlayer.
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Janardhanam, V.,Jyothi, I.,Sekhar Reddy, P.R.,Cho, Jaehee,Cho, Jeong-Mook,Choi, Chel-Jong,Lee, Sung-Nam,Rajagopal Reddy, V. Elsevier 2018 Superlattices and microstructures Vol.120 No.-
<P><B>Abstract</B></P> <P>The temperature-dependent current-voltage (<I>I-V</I>) characteristics of permalloy (Ni<SUB>0.8</SUB>Fe<SUB>0.2</SUB>) Schottky contacts to n-type GaN have been investigated. Magnetization measurements revealed the ferromagnetic behavior of Ni<SUB>0.8</SUB>Fe<SUB>0.2</SUB> film on n-type GaN. The Schottky barrier parameters, such as the barrier height and ideality factor, determined by thermionic emission depended on the measurement temperature, suggesting the presence of lateral inhomogeneity in the Schottky barrier. The experimental data modified by the thermionic emission model along with a Gaussian distribution of the barrier heights indicated the presence of a double Gaussian barrier distribution in the Ni<SUB>0.8</SUB>Fe<SUB>0.2</SUB>/n-type GaN Schottky contact. The mean barrier heights and standard deviations for each Gaussian distribution were 0.84 & 1.32 eV and 0.10 & 0.17 eV over temperature range of 125–200 K and 225–400 K, respectively. The noise spectral density of the current fluctuations measured as a function of frequency (<I>f</I>) at room temperature followed a 1/<I>f</I> <SUP> <I>γ</I> </SUP> dependence with a <I>γ</I> value close to unity, irrespective of the applied forward bias. The 1/<I>f-</I>type noise was attributed to the barrier inhomogeneity existing at the Ni<SUB>0.8</SUB>Fe<SUB>0.2</SUB>/n-type GaN Schottky interface as revealed from the temperature-dependent <I>I</I>–<I>V</I> characteristics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Ni<SUB>0.8</SUB>Fe<SUB>0.2</SUB>/n-type GaN structure showed ferromagnetic behavior. </LI> <LI> <I>I</I>–<I>V</I>–<I>T</I> characteristics of permalloy (Ni<SUB>0.8</SUB>Fe<SUB>0.2</SUB>)/n-GaN Schottky diodes were studied. </LI> <LI> Thermionic emission model with a Gaussian distribution of barriers indicates double barrier distribution. </LI> <LI> At 300 K, current noise spectral density against frequency (<I>f</I>) showed a 1/<I>f</I> dependence. </LI> <LI> 1/<I>f-</I>type noise was attributed to barrier inhomogeneity at the Ni<SUB>0.8</SUB>Fe<SUB>0.2</SUB>/n-type GaN Schottky interface. </LI> </UL> </P>
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