Browsing by Author "Tzeng, Ju-Yuan"

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Body-Tied Germanium Tri-Gate Junctionless PMOSFET With In-Situ Boron Doped Channel
(2014-01-01)
Chen, Che-Wei
;
Chung, Cheng-Ting
;
Tzeng, Ju-Yuan
;
Chang, Pang-Sheng
;
Luo, Guang-Li
In this letter, we demonstrate body-tied Ge tri-gate junctionless (JL) p-channel MOSFETs directly on Si. Our tri-gate JL-PFET exhibits higher current than the conventional inversion-mode transistor through in-situ heavily doped technique and trimming down Ge fin width. We show that the JL-PFET with tri-gate structure has excellent I-ON/I-OFF ratio and good short channel effect control on the channel potential. The current ratio is of similar to 6 x 10(3) (I-D) at V-DS = -0.1 V, V-GS = -3, and 0 V. The relatively low OFF-current is of 6 nA/ mu m at V-DS = -0.1 V and V-GS = 0 V. The subthreshold swing of 203 mV/decade and drain induced barrier lowering of 220 mV/V are reported at L-G = 120 nm.
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.
Germanium N and P Multifin Field-Effect Transistors With High-Performance Germanium (Ge) p(+)/n and n(+)/p Heterojunctions Formed on Si Substrate
(2013-04-01)
Chen, Che-Wei
;
Chung, Cheng-Ting
;
Tzeng, Ju-Yuan
;
Li, Pin-Hui
;
Chang, Pang-Sheng
We demonstrate the characteristics of p(+)-Ge/n-Si and n(+)-Ge/p-Si heterojunction diodes formed by heteroepitaxial Ge grown on Si leading to high performance and very low leakage current. The ON/OFF current ratio of the p(+)-Ge/n-Si and n(+)-Ge/p-Si heterojunction was >10(7) and >10(6), respectively. The OFF current density was extremely low at <10 mu A/cm(2) for the p(+)-Ge/n-Si formed with different implantation energies of 10 similar to 40 KeV and similar to 20 mu A/cm(2) for the n(+)-Ge/p-Si with different implantation energies of 20 similar to 50 KeV at a reverse bias of vertical bar V-R vertical bar = +/- 1 V, respectively. Both p and n-Ge channel multifin field-effect transistors (FinFETs) were formed by a mesa structure using these p(+)-Ge/n-Si and n(+)-Ge/p-Si heterojunctions. A high-kappa/metal gate stack was employed. The body-tied Ge multifin FinFET with a fin width (W-Fin) of similar to 40 nm, and the channel length (L-Channel) was 150 nm for p-FinFET and of 110 nm for n-FinFET, exhibiting a driving current of 174 mu A/mu m at V-G = -2 V and 102 mu A/mu m at V-G = 2 V, respectively. This is the first experimental demonstration of a body-tied high mobility Ge channel multifin FinFET using a top-down approach.
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.