Structural analysis and resistivity measurements of InAs and GaSb fins on 300 mm Si for vertical (T)FET

Abstract

We report on the uniform selective area growth of InAs and GaSb by metal-organic vapor phase epitaxy on a patterned shallow trench isolation SiO2/Si 300 mm template. High-quality InAs fins are realized via direct InAs nucleation on Si in the trenches. 60° interfacial misfit dislocation arrays formed along the {111} oriented InAs/Si interfaces accommodate most of the lattice mismatch such that threading dislocation generation from residual strain is minimized. GaSb grown on a thick GaAs buffer (partial filling of the trench) suffers from twin formation. The twin density is found to decrease with increasing growth temperature. To maximize the volume of low-defect density material inside the trench, the GaSb growth is initiated as close as possible to the trench bottom. Therefore, uniform high-quality GaSb fins are grown on a very thin low-temperature GaAs and the newly developed InAs seed in the V-groove. High-resolution x-ray diffraction reciprocal space maps show that the InAs and GaSb fins are nearly completely relaxed. The resistivity of undoped and n-doped InAs and undoped and p-doped GaSb fins is measured on as-grown material by micro-4-point-probe without the need for additional complicated device processing. The values are compared to those required for devices as presented in modeling papers. The result is encouraging for the ultra-large-scale integration of vertical nanowire III-V (tunnel) field-effect transistor on 300 mm Si.

Nano-Ridge Engineering of GaSb for the Integration of InAs/GaSb Heterostructures on 300 mm (001) Si

“…In order to study the impact of the GaAs surface, we also explored a sample where we added a GaAs buffer on top of a GaAs seed revealing a flat (001) surface. The sample design in this investigation is very similar to what was explored in [38], but the NR volume and size on top of the oxide is much more pronounced. In addition, all the samples in this investigation are fully relaxed based on (224) reciprocal space mappings (RSMs), and the reciprocal lattice point of the GaSb NR is exactly at the position of strain-free GaSb without any shift, as observed before.…”

“…In the same way, the GaAs buffer was grown under conditions used for the high temperature overgrowth. The InAs seed was deposited at 365 • C with a V/III ratio of 70 similar to the conditions reported before [38]. The GaSb overgrowth conditions, which were kept constant for all three GaSb samples, were slightly modified to 560 • C and a V/III ratio of 2 in comparison to [38] (530 • C and V/III of 1), and also the growth time was increased in order to achieve a pronounced NR with a funnel profile exposing a large (001) surface.…”

“…III/Sb tends to nucleate easily as three-dimensional islands on a Si surface [20,50,51], even at low growth temperatures. A further reduction in growth temperature to improve the wetting behavior leads to a diminishing growth rate, whereas a higher material flux into the chamber can cause selectivity issues on the oxide pattern [38]. In this investigation we inserted an InAs or a GaAs seed before a high temperature GaSb overgrowth to simplify the III-V nucleation on Si.…”

“…In this investigation we inserted an InAs or a GaAs seed before a high temperature GaSb overgrowth to simplify the III-V nucleation on Si. These seed layers cover the {111} planes at deposition temperature, but ramping up to the higher temperatures for the overgrowth leads to reflow exposing a slightly rounded V-shaped surface, as already discussed in [38]. In order to study the impact of the GaAs surface, we also explored a sample where we added a GaAs buffer on top of a GaAs seed revealing a flat (001) surface.…”

“…In our first investigation of GaSb SAG in V-grooved Si/SiO 2 trenches [38], we observed that the direct deposition of GaSb on Si does not easily lead to a good crystal quality and high selectivity, whereas the application of a thin InAs or GaAs seed layer clearly improves the GaSb integration on Si. Another important conclusion was that higher substrate temperatures are beneficial for the GaSb overgrowth to suppress planar defect formation.…”