Browsing by Author "Chien, Hung-Pin"

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Enhancing the Performance of Germanium Channel nMOSFET Using Phosphorus Dopant Segregation
(2014-01-01)
Chen, Che-Wei
;
Tzeng, Ju-Yuan
;
Chung, Cheng-Ting
;
Chien, Hung-Pin
;
Chien, Chao-Hsin
In this letter, we present a high performance Ge n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) with a NiGe Schottky junction source/drain fabricated using phosphorus dopant segregation. Phosphorus atoms were implanted into NiGe and then driven toward the NiGe/p-Ge interface to depin the Fermi level and form a Schottky junction. A high effective barrier height (Phi(Bp)) of 0.57 eV, resulting in a high junction current ratio of >10(4) at the applied voltage vertical bar V-a vertical bar = +/- 1 V. The nMOSFET exhibited a high I-ON/I-OFF ratio of similar to 8 x 10(3) (I-D), similar to 10(5) (I-S), and a subthreshold swing of 138 mV/decade. The nMOSFET developed in this letter exhibited greater transconductance and a drain leakage current that is more than two orders of magnitude lower compared with nMOSFETs with the conventional n(+)/p junction.
Experimental Realization of a Ternary-Phase Alloy Through Microwave-Activated Annealing for Ge Schottky pMOSFETs
(2016-07)
Hsu, Chung-Chun
;
Chi, Wei-Chun
;
Tsai, Yi-He
;
Chou, Chen-Han
;
Chen, Che-Wei
This paper presents a high-performance Ge p-channel MOSFET (pMOSFET) with NiGePt as a ternary-phase alloy of Schottky source/drain (S/D) formed through low-temperature microwave-activated annealing (MWA). We fabricated a NiGePt alloy contact with uniform crystallinity through structural engineering and MWA. We clarified the phenomena of thermal reaction and diffusion for forming ternary-phase alloys using MWA properties such as thermal dynamics and ionic transportation. The ternary-phase NiGePt alloy is crucial for improving the off-leakage current of the junction. A lower process temperature is beneficial for eliminating surface roughness and reducing alloy agglomeration of the Schottky contact S/D. Consequently, the fabricated NiGePt/n-Ge Schottky junction exhibited a high effective barrier height (Phi(Bn)) of 0.59 eV, resulting in a high junction current ratio of more than 10(5) at an applied voltage of vertical bar V-a vertical bar = 1 V. In addition, we exploited the advantages of low-temperature microwave annealing to fabricate the pMOSFET, which includes a GeO2 passivation layer and a Schottky S/D. Our ternary Schottky Ge pMOSFET (L = 4 mu m) exhibited high I-ON/I-OFF ratios of approximately 3.7x10(3)(I-D) and 1.3x10(5)(I-S) and a moderate subthreshold swing of 126 mV/dec.
High Performance Ge Schottky PMOSFETs with Ternary-Phase Alloy
(2016-01-01)
Hsu, Chung-Chun
;
Chi, Wei-Chun
;
Chou, Chen-Han
;
Chen, Che-Wei
;
Chien, Hung-Pin
This work demonstrates high-performance Ge p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) [1] with ternary-phase NiGePt alloy Schottky source/drain (S/D) by low-temperature microwave-activated annealing (MWA) [2]. Process flow of Shcottky junctions is shown in Fig. 1. Interestingly, the formed NiGePt alloy is nearly single crystalline. We found the formation of ternary-phase alloy NiGePt seems very helpful in suppressing the off-leakage of junction, as shown in Fig. 2. The fabricated NiGePt/N-Ge Schottky junction depicted an impressive effective barrier height (Phi(Bn)) of similar to 0.59 eV for electrons, leading to a high junction current ratio of >10(5) at the applied voltage of vertical bar V-a vertical bar = 1 V. Slight increase with increasing deposited Pt thickness can be explained by the improved series resistance, as shown in Fig. 2. The lower process temperature of MWA as compared to the conventional thermal annealing is beneficial for eliminating surface roughness, reducing alloy agglomeration of Schottky contact S/D. As a consequence, we employed the advantages of low-temperature MWA to fabricate the Schottky S/D PMOSFETs. With forming gas annealing, the Ge PMOSFET (L = 4 mu m) showed a very high output current of 33.5 mu A/mu m at V-GS-V-T = -2.4 and V-DS = -2 V. Our ternary Schottky PMOSFET exhibited a high I-ON/I-OFF ratios of similar to 3.7 X 10(3)(I-D) and similar to 1.3 X 10(5)(I-S), and a moderate subthreshold swing of 126 mV/dec, as shown in Figs. 3.
High-Performance Germanium p- and n-MOSFETs With NiGe Source/Drain
(2014-08-01)
Chen, Che-Wei
;
Tzeng, Ju-Yuan
;
Chung, Cheng-Ting
;
Chien, Hung-Pin
;
Chien, Chao-Hsin
In this paper, we report Ge p- and n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with NiGe source/drain (S/D) with high performance and low leakage current. The forward/reverse current ratio of the NiGe/n-Ge and NiGe/p-Ge junctions were similar to 10(5) and similar to 2 x 10(4) at vertical bar V vertical bar = +/- 1 V, respectively. Interface state densities Dit of Al2O3/GeO2/Ge stack is improved to be around 10(12)/eV(-1) cm(2) near the midgap after forming gas annealing; the gate-stack also shows excellent reliability under constant field stressing. Both p- and n-channel MOSFETs show sufficiently high ION/IOFF ratio. High driving current of similar to 9 and similar to 4 mu A/mu m at vertical bar V-GS - V-T vertical bar = +/-0.8 V and V-DS vertical bar = +/- V is obtained, respectively, for p- and n-MOSFETs. Moreover, S/D series resistance R-SD of the p- and n-MOSFET is reduced by similar to 25% and similar to 42% as compared with that of the transistors with conventional p/n junctions.