Mum Gate Length Research Articles

1 µm gate length, In 0.75 Ga 0.25 As channel, thin body n-MOSFET on InP substrate with transconductance of 737 µS/μm

The first demonstration of implant-free, flatband-mode In 0.75 Ga 0.25 As channel n-MOSFETs is reported. These 1 mum gate length MOSFETs, fabricated on a structure with average mobility of 7720 cm /Vs and sheet carrier concentration of 3.3 times 10 cm -2 , utilise a Pt gate, a high-k dielectric (k sime 20), and a delta-doped InAlAs/InGaAs/InAlAs heterostructure. The devices have a typical maximum drive current (I d,sat ) of 933 muA/mum, extrinsic transconductance (g m ) of 737 muS/mum, gate leakage (I g ) of 40 pA, and on-resistance (R on ) of 555 Omega .mum. The g m and R on figures of merit are the best reported to date for any III-V MOSFET.

Fabrication and Performance of 0.25-$\mu$m Gate Length Depletion-Mode GaAs-Channel MOSFETs With Self-Aligned InAlP Native Oxide Gate Dielectric

The fabrication and performance of 0.25- mum gate length GaAs-channel MOSFETs using the wet thermal native oxide of InAlP as the gate dielectric are reported. A fabrication process that self-aligns the gate oxidation to the gate recess and metallization to reduce the source access resistance is demonstrated for the first time. The fabricated devices exhibit a peak extrinsic transconductance of 144 mS/mm, an on-resistance of 3.46 Omega-mm, and a threshold voltage of -1.8 V for typical 0.25 -mum gate devices. A record cutoff frequency of 31 GHz for a GaAs-channel MOSFET and a maximum frequency of oscillation f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 47 GHz have also been measured.

0.25 $\mu\hbox{m}$ Self-Aligned AlGaN/GaN High Electron Mobility Transistors

Self-aligned AlGaN/GaN high electron mobility transistors grown on semiinsulating SiC substrates with a 0.25 mum gate-length were fabricated using a single-step ohmic process. Our recently developed Mo/Al/Mo/Au-based ohmic contact requiring annealing temperatures between 500degC and 600degC was utilized. Ohmic contact resistances between 0.35-0.6 Omega ldr mm were achieved. These 0.25 mum gate-length devices exhibited drain current density as high as 1.05 A/mm at a gate bias of 0 V and a drain bias of 10 V. A knee voltage of less than 2 V and a peak extrinsic transconductance (gm ) of 321 mS/mm were measured. For their microwave characteristics, a unity gain cutoff frequency (fT ) of 82 GHz and maximum frequency of oscillation (f max) of 103 GHz were measured.

Simulation and fabrication of submicron channel length DMOS transistors for analog applications

The use of an asymmetric MOS structure for superior analog circuit performance is considered. Results from the fabrication of 1- mu m-gate length DMOS transistors show increases of up to 1.9 in transconductance, 10 in output resistance, and 8 in intrinsic gain when compared to NMOS structures of similar gate length and threshold voltage. Substrate current is also reduced by up to a factor of 10. This represents the first reported results of submicron channel length DMOS transistors. The standard 7 degrees implantation angle has significant impact on DMOS fabrication and is shown to produce a usable asymmetric DMOS from an otherwise symmetric DMOS. An optimal implant energy and diffusion time are shown to exist for DMOS enhancement region formation. Two-dimensional process and device simulators have proved necessary to develop the DMOS process, as well as to qualitatively explain body effect reduction and threshold voltage determination. The DMOS process has successfully yielded experimental circuits including a single ended operational amplifier of folded cascode technology and a 101-state ring oscillator. >

0.2- mu m gate-length atomic-planar doped pseudomorphic Al/sub 0.3/Ga/sub 0.7/As/In/sub 0.25/Ga/sub 0.75/As MODFETs with f/sub T/ over 120 GHz

The authors report the DC and RF performance of nominally 0.2- mu m-gate length atomic-planar doped pseudomorphic Al/sub 0.3/Ga/sub 0.7/As/In/sub 0.25/Ga/sub 0.75/As modulation-doped field-effect transistors (MODFETs) with f/sub T/ over 120 GHz. The devices exhibit a maximum two-dimensional electron gas (2 DEG) sheet density of 2.4*10/sup 12/ cm/sup -2/, peak transconductance g/sub m/ of 530-570 mS/mm. maximum current density of 500-550 mA/mm, and peak current-gain cutoff frequency f/sub T/ of 110-122 GHz. These results are claimed to be among the best ever reported for pseudomorphic AlGaAs/InGaAs MODFETs and are attributed to the high 2 DEG sheet density, rather than an enhanced saturation velocity, in the In/sub 0.25/Ga/sub 0.75/As channel. >