A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is H.sub.2, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is Hz, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is H.sub.2, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

A method of performing heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and a second precursor gas, to form a heteroepitaxial growth of one of GaAs, AlAs, InAs, GaP, InP, ZnSe, GaSe, CdSe, InSe, ZnTe, CdTe, GaTe, HgTe, GaSb, InSb, AlSb, CdS, GaN, and AlN on the substrate; wherein the substrate comprises one of GaAs, AlAs, InAs, GaP, InP, ZnSe, GaSe, CdSe, InSe, ZnTe, CdTe, GaTe, HgTe, GaSb, InSb, AlSb, CdS, GaN, and AlN; wherein the carrier gas is H.sub.2, wherein the first precursor is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the second precursor is one of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide), H.sub.2S (hydrogen sulfide), and NH.sub.3 (ammonia). The process may be an HVPE (hydride vapor phase epitaxy) process.

A method of producing graphene or other two-dimensional material such as graphene including heating the substrate held within a reaction chamber to a temperature that is within a decomposition range of a precursor, and that allows two-dimensional crystalline material formation from a species released from the decomposed precursor; establishing a steep temperature gradient (preferably >1000° C. per meter) that extends away from the substrate surface towards an inlet for the precursor; and introducing precursor through the relatively cool inlet and across the temperature gradient towards the substrate surface. The steep temperature gradient ensures that the precursor remains substantially cool until it is proximate the substrate surface thus minimizing decomposition or other reaction of the precursor before it is proximate the substrate surface. The separation between the precursor inlet and the substrate is less than 100 mm.

A nanowire structure includes a substrate, a graded planar buffer layer, a patterned mask, and a nanowire. The graded planar buffer layer is on the substrate. The patterned mask is on the graded planar buffer layer and includes an opening through which the graded planar buffer layer is exposed. The nanowire is on the graded planar buffer layer in the opening of the patterned mask. A lattice constant of the graded planar buffer layer is between a lattice constant of the substrate and a lattice constant of the nanowire. By providing the graded planar buffer layer, lattice mismatch between the nanowire and the substrate can be reduced or eliminated, thereby improving the quality and performance of the nanowire structure.

A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is H.sub.2, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

A method of performing HVPE heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and ternary-forming gasses (V/VI group precursor), to form a heteroepitaxial growth of a binary, ternary, and/or quaternary compound on the substrate; wherein the carrier gas is Hz, wherein the first precursor gas is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the ternary-forming gasses comprise at least two or more of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), HzTe (hydrogen telluride), SbH.sub.3 (hydrogen antimonide, or antimony tri-hydride, or stibine), H.sub.2S (hydrogen sulfide), NH.sub.3 (ammonia), and HF (hydrogen fluoride); flowing the carrier gas over the Group II/III element; exposing the substrate to the ternary-forming gasses in a predetermined ratio of first ternary-forming gas to second ternary-forming gas (1tf:2tf ratio); and changing the 1tf:2tf ratio over time.

A method of performing heteroepitaxy comprises exposing a substrate to a carrier gas, a first precursor gas, a Group II/III element, and a second precursor gas, to form a heteroepitaxial growth of one of GaAs, AlAs, InAs, GaP, InP, ZnSe, GaSe, CdSe, InSe, ZnTe, CdTe, GaTe, HgTe, GaSb, InSb, AlSb, CdS, GaN, and AlN on the substrate; wherein the substrate comprises one of GaAs, AlAs, InAs, GaP, InP, ZnSe, GaSe, CdSe, InSe, ZnTe, CdTe, GaTe, HgTe, GaSb, InSb, AlSb, CdS, GaN, and AlN; wherein the carrier gas is Hz, wherein the first precursor is HCl, the Group II/III element comprises at least one of Zn, Cd, Hg, Al, Ga, and In; and wherein the second precursor is one of AsH.sub.3 (arsine), PH.sub.3 (phosphine), H.sub.2Se (hydrogen selenide), H.sub.2Te (hydrogen telluride), SbH.sub.3 (hydrogen antimonide), H.sub.2S (hydrogen sulfide), and NH.sub.3 (ammonia). The process may be an HVPE (hydride vapor phase epitaxy) process.

Transdermal microneedles continuous monitoring system is provided. The continuous system monitoring includes a substrate, a microneedle unit, a signal processing unit and a power supply unit. The microneedle unit at least comprises a first microneedle set used as a working electrode and a second microneedle set used as a reference electrode, the first and second microneedle sets arranging on the substrate. Each microneedle set comprises at least a microneedle. The first microneedle set comprises at least a sheet having a through hole on which a barbule forms at the edge. One of the sheets provides the through hole from which the barbules at the edge of the other sheets go through, and the barbules are disposed separately.