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Shim-Hoon Yuk,Hyun-Gwon Park,V. Janardhanam,Kyu-Hwan Shim,Sung-Nam Lee,Chel-Jong Choi 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.S1
We have investigated microstructural and electrical properties of self-aligned Ni-InGaAs alloy used as contact material toInGaAs as a function rapid thermal annealing (RTA) temperature. The Ni-InGaAs alloy was the only phase resulting fromsolid-state reaction between Ni and InGaAs, regardless of the RTA temperature. Microstructural evolutions of Ni-InGaAs andoverlaid Ni films were observed for increasing RTA temperature. The increase in RTA temperature resulted in increasing thesize of the pinholes formed in the Ni film, which could be associated with the columnar growth nature of sputter-deposited Nifilm. A relatively uniform Ni-InGaAs layer was formed after RTA at 300 oC, which could be responsible for the minimumspecific contact resistivity observed at this temperature. Above this temperature, the Ni-InGaAs layer underwent severestructural degradation such as the formation of microvoids in its surface area, leading to a rapid increase in specific contactresistivity.
Effect of Oxygen Plasma Treatment on the Electrical Characteristics of Pt/n-type Si Schottky Diodes
V. Janardhanam,I. Jyothi,Shim-Hoon Yuk,Chel-Jong Choi,Sung-Nam Lee,V. Rajagopal Reddy 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.8
The electrical properties of Pt/n-type Si Schottky diodes fabricated from n-type Si wafers subjected to an oxygen (O2) plasma treatment were investigated as a function of the power of the O2 plasma. The Pt/n-type Si Schottky diode with an O2 plasma treatment at a power of 100 W showed better rectifying characteristics with increasing barrier height and decreasing ideality factor compared to the conventional Pt/n-type Si Schottky diodes. This could be attributed to an improvement in the interface homogeneity associated with damage-free surface smoothing driven by the O2 plasma treatment at a power of 100 W. On the other hand, with increasing power of the O2 plasma for powers above 150 W, the barrier height decreased and the leakage current increased, indicating degradation of the device performance. The degradation in the rectifying properties after the O2 plasma treatment at a higher plasma power in excess of 150 W could be associated with increases in the series resistance and the interface state density caused by plasma-induced damage to the Si surface.
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.
Fermi-level depinning in metal/Ge interface using oxygen plasma treatment
Janardhanam, Vallivedu,Yun, Hyung-Joong,Jyothi, Inapagundla,Yuk, Shim-Hoon,Lee, Sung-Nam,Won, Jonghan,Choi, Chel-Jong Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.463 No.-
<P><B>Abstract</B></P> <P>Oxygen (O<SUB>2</SUB>) plasma treatment on germanium (Ge) surface was employed to depin Fermi-level in Al/n-type Ge interface. The Al contact to n-type Ge without and with O<SUB>2</SUB> plasma treatments for 1 and 2 min showed rectifying characteristics despite the low work function of Al, which could be associated with the Fermi-level pinning. An increase in O<SUB>2</SUB> plasma treatment time resulted in a decrease in Schottky barrier height along with the improvement of the homogeneity of Schottky interface. On the other hand, Al contact to O<SUB>2</SUB> plasma-treated n-type Ge for 3 min exhibited Ohmic behavior, implying the depinning of Fermi-level in Al/n-type Ge interface. A transition from rectifying to Ohmic behavior observed in Al/n-type Ge contact with O<SUB>2</SUB> plasma treatment for 3 min could be attributed to the more homogenous and stoichiometric formation of Ge-oxide layer. Such a high quality Ge-oxide layer effectively passivated unsatisfied surface states in Ge, which could be responsible for Fermi-level depinning of Ge.</P> <P><B>Highlights</B></P> <P> <UL> <LI> O<SUB>2</SUB> plasma treatment on Ge surface was employed to depin Fermi-level of Ge interface. </LI> <LI> Transition from Schottky to Ohmic behavior was observed in Al/n-type Ge with O<SUB>2</SUB> plasma treatment for 3 min. </LI> <LI> An increase in O<SUB>2</SUB> plasma treatment time led to the improved homogeneity of Schottky interface. </LI> <LI> More homogenous and stoichiometric Ge-oxide layer was formed after O<SUB>2</SUB> plasma treatment for 3 min. </LI> <LI> Ge surface passivation through Ge-oxide layer could be a main cause of depinning the Fermi-level of Ge. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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.
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.