GaAs microcrystals selectively grown on silicon: Intrinsic carbon doping during chemical beam epitaxy with trimethylgallium

Abstract

International audienceThe monolithic integration of III-V semiconductors on silicon and particularly of GaAs has aroused great interest since the 1980s. Potential applications are legion, ranging from photovoltaics to high mobility channel transistors. By using a novel integration method, we have shown that it is possible to achieve heteroepitaxial integration of GaAs crystals (typical size 1 lm) on silicon without any structural defect such as antiphase domains, dislocations, or stress, usually reported for direct GaAs heteroepitaxy on silicon. However, concerning their electronic properties, conventional free carrier characterization methods are impractical due to the micrometric size of GaAs crystals. In order to evaluate the GaAs material quality for optoelectronic applications, a series of indirect analyses such as atom probe tomography, Raman spectroscopy, and micro-photoluminescence as a function of temperature were performed. These revealed a high content of partially electrically active carbon originating from the trimethylgallium used as the Ga precursor. Nevertheless, the very good homogeneity observed by this doping mechanism and the attractive properties of carbon as a dopant once controlled to a sufficient degree are a promising route to device doping

Determination of n-Type Doping Level in Single GaAs Nanowires by Cathodoluminescence

“…The magnitude of this tail (red curve in Figure 6c) gives also an indication of the carrier concentration. A simple empirical relation is deduced from thin film reference samples: γ = × × − n 6.077 10 9 0.3476 (7) where n is expressed in cm −3 and the absorption tail γ in eV.…”

“…Recent development of optoelectronics takes advantage of light confinement in nanostructures such as lasers, light-emitting diodes, solar cells, and hybrid III–V/Si devices. − Optimal performances require the control and the characterization of semiconductor doping with submicrometer characteristic lengths for both the p and the n regions. Radial junctions in nanowires are a noteworthy example. , III–V semiconductor nanowires (NWs) may constitute a new route toward high-efficiency photovoltaic cells. , Nanowire arrays show anti-reflection properties and are beneficial for absorbing tilted incident or diffuse sunlight .…”