GaSb inversion-mode PMOSFETs with atomic-layer-deposited (ALD) Al2O3 as gate dielectric are demonstrated. A 0.75- μm-gate-length device has a maximum drain current of 70 mA/mm, a transconductance of 26 mS/mm, and a hole inversion mobility of 200 cm2/V ·s. The off-state performance is improved by reducing the ALD growth temperature from 300°C to 200°C. The measured interface trap distribution shows a low interface trap density of 2 × 1012/cm2·eV near the valence band edge. However, it increases to 1 - 4 ×1013/cm2 ·eV near the conduction band edge, leading to a drain current on-off ratio of 265 and a subthreshold swing of ~ 600 mV/decade. GaSb, similar to Ge, is a promising channel material for PMOSFETs due to its high bulk hole mobility, high density of states at the valence band edge, and, most importantly, its unique interface trap distribution and trap neutral level alignment.

/pdf/gasb-inversion-mode-pmosfets-with-atomic-layer-deposited-4mdds4ojtx.pdf

GaSb Inversion-Mode PMOSFETs With Atomic-Layer-Deposited $\hbox{Al}_{2}\hbox{O}_{3}$ as Gate Dielectric

Ultrathin-body InAsSb-on-insulator n-type field-effect transistors (FETs) with ultrahigh electron mobilities are reported. The devices are obtained by the layer transfer of ultrathin InAs0.7Sb0.3 layers (thickness of 7-17 nm) onto Si/SiO2 substrates. InAsSb-on-insulator FETs exhibit an effective mobility of ~ 3400 cm2/V·s for a body thickness of 7 nm, which represents ~ 2× enhancement over InAs devices of similar thickness. The top-gated FETs deliver an intrinsic transconductance of ~ 0.56 mS/μm (gate length of ~ 500 nm) at VDS = 0.5 V with ION/IOFF of 102-103. These results demonstrate the utility of the transfer process for obtaining high-mobility n-FETs on Si substrates by using mixed anion arsenide-antimonide as the active channel material.

/pdf/ultrathin-body-high-mobility-inassb-on-insulator-field-159v84e8r1.pdf

Ultrathin-Body High-Mobility InAsSb-on-Insulator Field-Effect Transistors

Experimental gate capacitance (Cg) versus gate voltage data for InAs0.8Sb0.2 quantum-well MOSFET (QW-MOSFET) is analyzed using a physics-based analytical model to obtain the quantum capacitance (CQ) and centroid capacitance (Ccent). The nonparabolic electronic band structure of the InAs0.8Sb0.2 QW is incorporated in the model. The effective mass extracted from Shubnikov-de Haas magnetotransport measurements is in excellent agreement with that extracted from capacitance measurements. Our analysis confirms that in the operational range of InAs0.8Sb0.2 QW-MOSFETs, quantization and nonparabolicity in the QW enhance CQ and Ccent. Our quantitative model also provides an accurate estimate of the various contributing factors toward Cg scaling in future arsenide-antimonide MOSFETs.

/pdf/experimental-determination-of-quantum-and-centroid-5ci7gyu301.pdf

Experimental Determination of Quantum and Centroid Capacitance in Arsenide–Antimonide Quantum-Well MOSFETs Incorporating Nonparabolicity Effect

This letter demonstrates, for the first time, enhancement-mode (e-mode) antimonide MOSFETs by integrating a composite high-κ gate stack (3 nm Al2O3 -1 nm GaSb) with an ultrathin InAs0.7Sb0.3 quantum well (7.5 nm). The MOSFET exhibits record high electron drift mobility of 5200 cm2/V · s at carrier density (Ns) of 1.8 × 1012 cm-2, subthreshold slope of 150 mV/dec, ION/IOFF ratio of ~4000× within a voltage window of ~1 V, high ION of 40 μA/μm at VDS of 0.5 V for a 5-μm gate length (LG) device. The device exhibits excellent pinchoff in the output characteristics with no evidence of impact ionization enabled by enhanced quantization and e-mode operation. RF characterization allows extraction of the intrinsic device metrics (Cgs, Cgd, gm, veff and ft) and the parasitic resistive and capacitive elements limiting the short-channel device performance.

http://www.nrl.navy.mil/estd/sites/www.nrl.navy.mil.estd/files/pdfs/11-1226-3596.pdf

Enhancement-Mode Antimonide Quantum-Well MOSFETs With High Electron Mobility and Gigahertz Small-Signal Switching Performance

In this paper, the scalability of In0.7Ga0.3As QWFET is investigated using two-dimensional numerical drift–diffusion simulation. Numerical drift–diffusion simulations were calibrated using experimental results on short-channel In0.7Ga0.3As QWFETs [7] to include the effects of velocity overshoot. Logic figures of merit (sub-threshold slope, saturated threshold voltage, drain induced barrier lowering, ION/IOFF ratio over a specified gate swing, effective injection velocity and intrinsic switching delay) extracted from the numerical simulations are in excellent agreement with the experimental data. Three alternate QWFET device architectures are proposed and thoroughly investigated for 15 nm node and beyond logic applications. Amongst them, double-gate In0.7Ga0.3As QWFET shows the best scalability in terms of logic figures of merit, thus making it an ideal candidate for the design and demonstration of the ultimate scaled transistor.

/pdf/investigation-of-scalability-of-in0-7ga0-3as-quantum-well-5773f1yfk7.pdf

Investigation of scalability of In0.7Ga0.3As quantum well field effect transistor (QWFET) architecture for logic applications

This paper demonstrates the integration of a composite high-κ gate stack (3.3 nm Al 2 O 3 −1.0 nm GaSb) with a mixed anion InAs 0.8 Sb 0.2 quantum-well field effect transistor (QWFET). The composite gate stack achieves; (i) EOT of 4.2 nm with &#60;10−7A/cm2 gate leakage (ii) low D it interface (∼1×1012 /cm2/eV) (iii) high drift µ of 3,900–5,060 cm2/V-s at N S of 5×1011−3×1012/cm2. The InAs 0.8 Sb 0.2 MOS-QWFETs with composite gate stack exhibit extrinsic (intrinsic) g m of 334 (502) µS/µm and drive current of 380 µA/µm at V DS = 0.5V for Lg=1µm.

/pdf/advanced-composite-high-k-gate-stack-for-mixed-anion-45b7k4fk2q.pdf

I. Geppert

Papers

Advanced composite high-κ gate stack for mixed anion arsenide-antimonide quantum well transistors