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.
Chemical beam epitaxy of Ga0.47In0.53As/InP quantum wells and heterostructure devices
Abstract Chemical beam epitaxy (CBE) is the newest development in epitaxial growth technology. It combines many important advantages of molecular beam epitaxy (MBE) and organometallic chemical vapor deposition (OMCVD). This paper briefly reviews some of the recent progress in the preparation of Ga 0.47 In 0.53 As/InP heterostructures and devices by CBE in our laboratories. Extreme composition uniformity has been obtained for Ga 0.47 In 0.53 As epilayers which exhibited excitonic transitions with linewidths (full-width at half-maxima) as narrow as 1.2 meV at 2K. Such linewidth represents the narrowest ever obtained for GaInAs grown by any technique. Similarly, Ga 0.47 In 0.53 As/InP single quantum wells with thickness as thin as 6 A have 2 K photoluminescence linewidths substantially narrower than all previous reported values. These linewidths indicate the “effective” interface roughness to be 0.12 lattice constant. Double-heterostructure p-i-n photodetectors exhibited high quantum efficiency of 70% (without anti-reflection coating) and 0.47 In 0.53 As/InP double-heterostructure and multiquantum well lasers emitting at 1.47−1.72 μm have threshold current densities of 1.3 and 1.5 kA/cm 2 . Such values are the best reported so far. An improvement in the threshold-temperature dependence in multiquantum well lasers was also demonstrated unambiguously for the first time. Two-dimensional electron gas mobilities at the Ga 0.47 In 0.53 As/InP hetero-interfaces were as high as 130 × 10 3 cm 2 /V·s at 4.2 K. Such mobilities are higher than those obtained by other growth techniques. Quantum Hall effect and shubnikov-De Haas measurements also demonstrated the extremely high quality of the Ga 0.47 In 0.53 As/InP hetero-interfaces. Our results undisputedly established CBE as a superior technique for producing extremely high quality Ga 0.47 In 0.53 As/InP heterostructures and quantum wells and advanced the epitaxial growth technology beyond both MBE and OMCVD.
Epitaxie par jets moléculaires de In0.53Ga0.47As et de InP sur substrats de InP
High purity In 0.53 Ga 0.47 As layers, lattice matched to InP, have been grown by molecular beam epitaxy (M.B.E.). Residual impurities levels are in the range of 10 15 cm −3 with electron mobilities up to 47000 cm 2 /V.s at 77 K. The high quality of the epilayers is obtained by controlling the substrate preparation, the substrate temperature, the arsenic pressure and the baking of the source materials. The layers are characterized by X-ray diffraction, Hall effect and low temperature photoluminescence. Doping levels are controlled between 10 16 cm −3 and 10 19 cm −3 , with thin for n-type and beryllium for p-type. Our first results on M.B.E. of InP are also reported Les concentrations d'impuretes residuelles dans In 0,53 Ga 0,47 As sont de l'ordre de 10 15 cm −3 , avec des mobilites electroniques allant jusqu'a 47000 cm 2 /V.s a 77 K. La bonne qualite des couches est obtenue en controlant la preparation du support, la temperature du support, la pression d'arsenic et le recuit des produits sources. Caracterisation par diffraction RX, effet Hall et photoluminescence a basse temperature