Browsing by Author "Liao, P. H."

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Self-organized gate stack of Ge nanosphere/SiO2/Si1-xGex enables Ge-based monolithically-integrated electronics and photonics on Si platform
(2018-01-01)
Liao, P. H.
;
Kuo, M. H.
;
Tien, C. W.
;
Chang, Y. L.
;
Hong, P. Y.
We report the first-of-its-kind, self-organized gate stack of Ge nanosphere (NP) gate/SiO2/Si1-xGex channel fabricated in a single oxidation step. Process-controlled tunability of the Ge NP size (5-90nm), SiO2 thickness (2-4nm), and Ge content (x = 0.65-0.85) and strain engineering (epsilon(comp) = 1-3%) of the Si1-xGex are achieved. We demonstrated Ge junctionless (JL) n-FETs and photoMOSFETs (PTs) as amplifier and photodetector, respectively, for Ge receivers. L-G of 75nm JL n-FETs feature I-ON/I-OFF > 5x10(8), I-ON > 500 mu A/mu m at V-DS = 1V, T= 80K. Ge-PTs exhibit superior photoresponsivity > 1,000A/W and current gain linearity ranging from nW-mW for 850nm illumination. Size-tunable photo-luminescence (PL) of 300-1600nm (NUV-NIR) are observed on 5-100nm Ge NPs. Our gate stack of Ge NP/SiO2/Si1-xGex enables a practically achievable building block for monolithically-integrated Ge electronic and photonic ICs (EPICs) on Si.
Single-fabrication-step Ge nanosphere/SiO2/SiGe heterostructures: a key enabler for realizing Ge MOS devices
(2018-05-18)
Liao, P. H.
;
Peng, K. P.
;
Lin, H. C.
;
George, T.
;
Li, P. W.
We report channel and strain engineering of self-organized, gate-stacking heterostructures comprising Ge-nanosphere gate/SiO2/SiGe-channels. An exquisitely-controlled dynamic balance between the concentrations of oxygen, Si, and Ge interstitials was effectively exploited to simultaneously create these heterostructures in a single oxidation step. Process-controlled tunability of the channel length (5-95 nm diameters for the Ge-nanospheres), gate oxide thickness (2.5-4.8 nm), as well as crystal orientation, chemical composition and strain engineering of the SiGe-channel was achieved. Single-crystalline (100) Si1-xGex shells with Ge content as high as x = 0.85 and with a compressive strain of 3%, as well as (110) Si1-xGex shells with Ge content of x = 0.35 and corresponding compressive strain of 1.5% were achieved. For each crystal orientation, our high Ge-content, highly-stressed SiGe shells feature a high degree of crystallinity and thus, provide a core 'building block' required for the fabrication of Ge-based MOS devices.