Hydride vapour phase epitaxy (HVPE) is an

epitaxial Epitaxy refers to a type of crystal growth or material deposition in which new crystalline layers are formed with one or more well-defined orientations with respect to the crystalline seed layer. The deposited crystalline film is called an epit ...

growth technique often employed to produce

semiconductors A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

such as GaN, GaAs, InP and their related compounds, in which

hydrogen chloride The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride ga ...

is reacted at elevated temperature with the group-III metals to produce gaseous metal chlorides, which then react with

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...

to produce the group-III nitrides. Carrier gasses commonly used include

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

and various

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts ...

s. HVPE technology can significantly reduce the cost of production compared to the most common method of vapor deposition of organometallic compounds (

MOCVD Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. ...

). Cost reduction is achieved by significantly reducing the consumption of NH3, cheaper source materials than in MOCVD, reducing the capital equipment costs, due to the high growth rate. Developed in the 1960s, it was the first epitaxial method used for the fabrication of single GaN crystals. Hydride Vapour Phase Epitaxy (HVPE) is the only III-V and III-N semiconductor crystal growth process working close to equilibrium. That means that the condensation reactions exhibit fast kinetics: one observes immediate reactivity to an increase of the vapour phase supersaturation towards condensation. This property is due to the use of chloride vapour precursors GaCl and InCl, of which dechlorination frequency is high enough so that there is no kinetic delay. A wide range of growth rates, from 1 to 100 microns per hour, can then be set as a function of the vapour phase supersaturation. Another HVPE feature is that growth is governed by surface kinetics: adsorption of gaseous precursors, decomposition of ad-species, desorption of decomposition products, surface diffusion towards kink sites. This property is of benefit when it comes to selective growth on patterned substrates for the synthesis of objects and structures exhibiting a 3D morphology. The morphology is only dependent on the intrinsic growth anisotropy of crystals. By setting experimental growth parameters of temperature and composition of the vapour phase, one can control this anisotropy, which can be very high as growth rates can be varied by an order of magnitude. Therefore, we can shape structures with various novel aspect ratios. The accurate control of growth morphology was used for the making of GaN quasi-substrates, arrays of GaAs and GaN structures on the micrometer and submicrometer scales, GaAs tips for local spin injection. Fast dechlorination property is also used for the VLS growth of GaAs and GaN nanowires with exceptional length.

References

Thin film deposition Semiconductor device fabrication {{Engineering-stub