We demonstrate for the first time 85nm gate length enhancement and depletion mode InSb quantum well transistors with unity gain cutoff frequency, f T , of 305 GHz and 256 GHz, respectively, at 0.5V V DS , suitable for high speed, very low power logic applications. The InSb transistors demonstrate 50% higher unity gain cutoff frequency, f T , than silicon NMOS transistors while consuming 10 times less active power.

This paper describes for the first time, a high-speed and low-power III-V p-channel QWFET using a compressively strained InSb QW structure. The InSb p-channel QW device structure, grown using solid source MBE, demonstrates a high hole mobility of 1,230cm 2 /V-s. The shortest 40nm gate length (L G ) transistors achieve peak transconductance (G m ) of 510μS/μm and cut-off frequency (f T ) of 140GHz at supply voltage of 0.5V. These represent the highest G m and f T ever reported for III-V p-channel FETs. In addition, effective hole velocity of this device has been measured and compared to that of the standard strained Si p-channel MOSFET. IntroductionThe III-V compound semiconductor quantum-well field effect transistor (QWFET) is one of the most promising device candidates for future high-speed, low-power logic applications due to its high electron mobility. Recently, highperformance III-V n-channel QWFETs have been demonstrated [1][2][3][4]. However, for implementation of CMOS logic, there is a significant challenge of identifying high mobility III-V p-channel candidates [5]. In this work, we demonstrate for the first time a high-speed and low-power III-V p-channel QWFET using a compressively strained InSb QW structure, which achieves cut-off frequency (f T ) of 140GHz at transistor gate length (L G ) of 40nm and supply voltage (V CC ) of 0.5V. This represents the highest f T ever reported for III-V p-channel FETs.

The mobility and carrier concentration of a number of InSb-based modulation-doped quantum well heterostructures are examined over a range of temperatures between 4.5 and 300 K. Wide well ͑30 nm͒ and narrow well ͑15 nm͒ structures are measured. The temperature dependent mobilities are considered within a scattering model that incorporates polar optical and acoustic phonon scatterings, interface roughness scattering, and scattering from charged impurities both in the three-dimensional background and within a distributed "quasitwo-dimensional" doping layer. Room temperature mobilities as high as 51 000 cm 2 / V s are reported for heterostructures with a carrier concentration of 5.8ϫ 10 11 cm −2 , while low-temperature mobility ͑below 40 K͒ reaches 248 000 cm 2 / V s for a carrier concentration of 3.9ϫ 10 11 cm −2. A Schrödinger-Poisson model is used to calculate band structures in the material and is shown to accurately predict carrier concentrations over the whole temperature range. Low-temperature mobility is shown to be dominated by remote ionized impurity scattering in wide well samples and by a combination of ionized impurity and interface roughness scattering in narrow well samples.

The heterogeneous integration of InSb quantum well transistors onto silicon substrates is investigated for the first time. 85 nm gate length FETs with f T ¼ 305 GHz at V ds ¼ 0.5 V and DC performance suitable for digital logic are demonstrated on material with a buffer just 1.8 mm thick. An initial step towards integrating InSb FETs with mainstream Si CMOS for high-speed, energy-efficient logic applications has been achieved.

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We report measurements of the electron g-factor in InSb quantum wells using the coincidence technique, polarization transition, and temperature-dependent resistivity. All three methods show that there is a giant enhancement of the spin slitting which is proportional to the spin polarization. Electron Zeeman energies as high as 51 meV are measured leading to the conclusion that the additional contribution to the spin splitting is of order 30 meV, more than ten times larger than expected from conventional theories.

Fourier transform infrared absorption measurements are presented from the dilute nitride semiconductor GaNSb with nitrogen incorporations between 0.2% and 1.0%. The divergence of transitions from the valence band to E − and E + can be seen with increasing nitrogen incorporation, consistent with theoretical predictions. The GaNSb band structure has been modeled using a five-band k · p Hamiltonian and a band anticrossing fitting has been obtained using a nitrogen level of 0.78 eV above the valence band maximum and a coupling parameter of 2.6 eV. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2349832͔It is well documented that the anion substitution of dilute quantities of nitrogen into III-V semiconductor compounds results in a sharp decrease in the band gap of the material from that of the host compound. A number of explanations have been suggested to describe this band gap reduction, most notably the band anticrossing model ͑BAC͒, calculations based on empirical pseudopotential methods, and interpretations based on the mixing of the ⌫, L, and X character of the conduction band states. The origin of this band gap reduction is the isoelectronic nature of the nitrogen atoms in the host III-V material. Though the nitrogen atom has the same electron valence as the atom it is replacing, its physical properties ͑size, electronegativity, bond length, etc.͒ are significantly different, resulting in a considerable, highly localized perturbation to the electronic potential surrounding the atom.According to the BAC model this localized deformation in potential results in the formation of an energy level extended in k space which may be resonant with the conduction band of the host. The interaction between the host conduction band and resonant nitrogen level results in the formation of two nonparabolic subbands ͑conventionally denoted E − and E + ͒ given by the relationwhere V MN is the matrix element describing the coupling between the host conduction band ͑E M ͒ and the resonant nitrogen level ͑E N ͒ and has the functional form V MN = C MN ͱ x where C MN is the coupling parameter and x is the nitrogen concentration. 2Nitrogen induced band gap reduction has been observed in many alloys including GaNP, 3 GaNAs, 4 InNAs, 5 and most recently GaNSb. 6 The addition of antimony to the dilute nitride GaNAs has been shown to improve the optical and electronic properties of the material 7 and has been suggested as a possible material for long wavelength optoelectronic devices lattice matched to GaAs. 8 To determine the dependence of the band gap of such materials as a function of nitrogen incorporation, the BAC parameters of the constituent endpoint ternaries must be known. Though these have been well investigated in GaNAs a lack of data is found for GaNSb, a fact highlighted in Vurgaftman and Meyer's review on nitrogen containing III-V materials. 9In this letter, Fourier transform infrared ͑FTIR͒ absorption measurements of GaNSb samples with nitrogen incorporations between 0.2% and 1.0% are presented and preliminary values f...