Bi-induced highly n-type carbon-doped InGaAsBi films grown by molecular beam epitaxy

Characterization of low-resistance ohmic contacts to heavily carbon-doped n-type InGaAsBi films treated by rapid thermal annealing*

“…Figure 3 shows the dependence of carrier concentration and mobility on CBr 4 supply pressure for n-type InGaAsBi grown at 275 • C in previous work [18] and n-type InGaAsBi annealed at 200 • C for 2 min duration in this work. As shown in Fig.…”

“…Growth details can be found in Ref. [18]. Hall-effect measurements with indium dots as ohmic contacts located on the sample periphery were performed to measure the electronic transport properties of these samples taken from half of the wafer.…”

“…As-annealing treatment eliminates defects and improves the electrical properties of carbon-doped InGaAsBi films and, meanwhile, drives more C onto group-III sites as donors, which increases the electron concentration and mobility. [18] A possible mechanism is that as-annealing treatment eliminates Bi-related defects, [28][29][30] drives more Bi onto group-V sites, and increases the number of activated carbon donors by forming C-Bi bonds around the Bi-related defects. [18] Besides, a self-compensation and the incorporation of the carbon atoms in interstitial sites may also be part of the reasons.…”

“…Further efforts are needed to reduce contact resistance, such as fine-tuning of surface preparation procedures and various alloy-contact selection. [16] It has been recently reported that dilute InGaAsBi, latticematched to InP, is promising to be used as a contact mate-rial for InP terahertz devices because of its higher doping solubility limit [17,18] and narrower band gap compared with InGaAs [19,20] by virtue of bismuth being a very heavy and large atom and the valence band anticrossing (VBAC). [21][22][23] The author's previous work has first proved that bismuth incorporation into InGaAs induces extremely high n-type carbondoped InGaAsBi films, and its carrier concentration can exceed 10 21 cm −3 , which is almost two orders of magnitude higher than the doping concentration of silicon in InGaAs.…”

“…[21][22][23] The author's previous work has first proved that bismuth incorporation into InGaAs induces extremely high n-type carbondoped InGaAsBi films, and its carrier concentration can exceed 10 21 cm −3 , which is almost two orders of magnitude higher than the doping concentration of silicon in InGaAs. [18] It implies that a lower specific contact resistance of InGaAsBi can be obtained than that of InGaAs according to the tunneling effect. [24] To fully make use of its potentials for high-speed electronics device fabrication, we have investigated the electrical properties and contact resistance of n-type carbon-doped InGaAsBi films with and without rapid thermal annealing (RTA).…”