Height-selective etching for regrowth of self-aligned contacts using MBE
Advanced III-V transistors require unprecedented low-resistance contacts in order to simultaneously scale bandwidth, f max and f t with the physical active region [M.J.W. Rodwell, M. Le, B. Brar, in: Proceedings of the IEEE, 96, 2008, p. 748]. Low-resistance contacts have been previously demonstrated using molecular beam epitaxy (MBE), which provides active doping above 4 x 10 19 cm -3 and permits in-situ metal deposition for the lowest resistances [U. Singisetti, M.A. Wistey, J.D. Zimmerman, B.J. Thibeault, M.J.W. Rodwell, A.C. Gossard, S.R. Bank, Appl. Phys. Lett., submitted]. But MBE is a blanket deposition technique, and applying MBE regrowth to deep-submicron lateral device dimensions is difficult even with advanced lithography techniques. We present a simple method for selectively etching undesired regrowth from the gate or mesa of a III-V MOSFET or laser, resulting in self-aligned source/drain contacts regardless of the device dimensions. This turns MBE into an effectively selective area growth technique.
High transconductance surface channel In0.53Ga0.47As MOSFETs using MBE source-drain regrowth and surface digital etching
We demonstrate In<sub>0.53</sub>Ga<sub>0.47</sub>As surface channel MOSFETs using a gate-last process and MBE source/drain (S/D) regrowth. The structure uses a sacrificial N+ InGaAs channel cap layer between the regrown S/D contact layer and the channel, which is removed in the channel region by a “digital” etch process incorporating UV ozone oxidation and surface stripping in dilute HCl. A device with 65 nm-L<sub>g</sub> and 1.2 nm EOT shows 1.6 mS/μm peak transconductance at V<sub>ds</sub> = 0.5 V and 120 mV/dec SS at V<sub>ds</sub> = 0.05 V, while 535 nm-L<sub>g</sub> devices show 95 mV/dec SS at at V<sub>ds</sub> = 0.1 V.
First observation of the quantum Hall effect in a Ga0.47In0.53As‐InP heterostructure with three electric subbands
Shubnikov–de Haas and quantum Hall effects have been studied in GaInAs‐InP heterojunctions grown by modified low pressure metalorganic chemical vapor deposition. In contrast to the results reported up till now on GaInAs‐InP heterojunctions with nearly the same channel electron density, not one but three electric subbands, E0, E1, and E2, are occupied in zero magnetic field. Two electric subbands E0 and E1 contribute to the quantum Hall effect. Magnetic depopulation of the higher (E1 and E2) subbands is observed in both perpendicular and tilted magnetic field orientations. This enables a demonstration of the importance of intersubband scattering in resistivity and cyclotron resonance.