Si Doping of Vapor–Liquid–Solid GaAs Nanowires: n-Type or p-Type?

Abstract

The incorporation of Si into vapor−liquid−solid GaAs nanowires often leads to p-type doping, whereas it is routinely used as an n-dopant of planar layers. This property limits the applications of GaAs nanowires in electronic and optoelectronic devices. The strong amphoteric behavior of Si in nanowires is not yet fully understood. Here, we present the first attempt to quantify this behavior as a function of the droplet composition and temperature. It is shown that the doping type critically depends on the As/Ga ratio in the droplet. In sharp contrast to vapor−solid growth, the droplet contains very few As atoms, which enhance their reverse transfer from solid to liquid. As a result, Si atoms preferentially replace As in GaAs, leading to p-type doping in nanowires. Hydride vapor phase epitaxy provides the highest As concentrations in the catalyst droplets during their vapor−liquid−solid growth, resulting in n-type dopant behavior of Si. We present experimental data on n-doped Sidoped GaAs nanowires grown by this method and explain the doping within our model. These results give a clear route for obtaining n-type or p-type Si doping in GaAs nanowires and may be extended to other III−V nanowires.

Awl‐like HfC nanowires grown on carbon cloth via Fe‐catalyzed in a polymer pyrolysis route

“…The vapor‐liquid‐solid (VLS) method is mainly used to explain many 1D nanostructures like SiCNWs, III‐V NWs, in which the liquid droplets are formed to promote the growth of 1D nanostructures. Based on the above analysis, apparently, the growth of HfC nanowires can be attributed to the VLS mechanism, which was analyzed for most of the 1D nanostructure growth.…”

Effect of Arsenic Depletion on the Silicon Doping of Vapor–Liquid–Solid GaAs Nanowires

“…Dependence of the amphoteric properties of silicon (that is, its ability to incorporate into either gallium or arsenic sites of GaAs) on the growth environment is long known, [22] with VLS NWs being the extreme case of the lowest chemical potential difference between arsenic and gallium species in a mother phase. [21] Chemical potential of arsenic atoms in liquid oscillates over the ML formation cycle as discussed earlier. Silicon may incorporate into GaAs at any time and hence the rate of replacing arsenic atoms becomes timedependent.…”

“…Silicon, which is a standard n-type dopant for planar GaAs layers in molecular beam epitaxy (MBE), often becomes p-type dopant in VLS GaAs NWs. [16][17][18][19][20][21] P-type silicon doping of GaAs NWs has been attributed to a much lower arsenic concentration in liquid (ternary Au-Ga-As or binary Ga-As) compared with gallium. [21] This enhances the probability to replace arsenic atoms with silicon relative to the vapor-solid growth of planar layers, which usually proceeds under arsenic-rich conditions.…”

“…[16][17][18][19][20][21] P-type silicon doping of GaAs NWs has been attributed to a much lower arsenic concentration in liquid (ternary Au-Ga-As or binary Ga-As) compared with gallium. [21] This enhances the probability to replace arsenic atoms with silicon relative to the vapor-solid growth of planar layers, which usually proceeds under arsenic-rich conditions. Dependence of the amphoteric properties of silicon (that is, its ability to incorporate into either gallium or arsenic sites of GaAs) on the growth environment is long known, [22] with VLS NWs being the extreme case of the lowest chemical potential difference between arsenic and gallium species in a mother phase.…”

“…Electronic and optoelectronic applications of III–V NWs require their controllable doping. Silicon, which is a standard n‐type dopant for planar GaAs layers in molecular beam epitaxy (MBE), often becomes p‐type dopant in VLS GaAs NWs . P‐type silicon doping of GaAs NWs has been attributed to a much lower arsenic concentration in liquid (ternary Au–Ga–As or binary Ga–As) compared with gallium .…”