PL182968B1 - Method fo obtaining gallium nitride monocrystals and epitaxial layers - Google Patents

Description

The present invention relates to a method of producing monocrystalline and monocrystalline gallium nitride layers. GaN is a semiconductor with a high band gap and is used in the production of photodiodes and lasers that emit ultraviolet or blue light. This compound retains its semiconductor properties up to high temperature (much higher than silicon) and is therefore predisposed for the production of semiconductor components operating at high temperatures, in the control of combustion and aircraft engines, as well as in metallurgy and geological drilling.

The European Patent No. 0401972 describes a batch method for the preparation of gallium nitride and several other elements, in which metal chloride is reacted with ammonia in a low-temperature plasma. The disadvantage of the method is the relatively high costs of equipment and energy, and the introduction of chloride ions into the reaction system, which is disadvantageous in the case of using the GaN thus obtained in electronics.

Russian Patent No. 683,505 describes a method of obtaining polycrystalline GaN powder by reacting liquid gallium with ammonia at a temperature of 380-420 ° C. LiH has been found to act as a catalyst for this reaction. However, single crystals and epitaxial layers cannot be obtained with this method.

The method of obtaining monocrystalline GaN layers is described in the international patent specification No. WO 92/16966. A beam of molecular gallium gas and activated atomic and ionic nitrogen are supplied to the growth chamber. The process consists of two stages: a low-temperature nucleation stage at 100-400 ° C and a high-temperature growth stage at 600-900 ° C. The preferred source of activated nitrogen is plasma derived from an electron microwave resonance cyclotron. This method is very complicated and expensive. The main disadvantage is the need to ionize nitrogen.

In the international patent specification No. WO 94/18120 a method of obtaining gallium nitride and nitrides of several other elements is presented. The liquid gallium reacts with the ammonia in the ball mill at 28-100 ° C. Again, the reaction product is a fine powder, not a single crystal.

US 005122845 describes a method for the preparation of gas-phase monocrystalline GaN layers on a sapphire substrate using various organometallic gallium compounds. The disadvantage of this method is the use of organometallic compounds as a substrate. The process is therefore extended by the step of obtaining these compounds. It is not without significance that they are flammable compounds.

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The aim of the invention was to develop a technologically uncomplicated method of obtaining gallium nitride single crystals and epitaxial layers, using the most readily available substrates.

The method of producing gallium nitride monocrystals and epitaxial layers according to the invention is characterized in that a portion of gallium metal is placed in a vessel arranged in a horizontal tube in a stream of a carrier gas such as N2, H2 or an inert gas such as Ar or He in the first zone of the furnace pipe, at a temperature of 100-1400 ° C. The carrier gas is fed at a rate of 0.1-20 cm / s. The gallium vapors are transferred by the carrier gas to the second zone of the furnace to which the ammonia stream is fed at a rate of 0.1-20 cm / s. In the second zone, a substrate made of silicon nitride, silicon carbide or aluminum trioxide is placed and the temperature is maintained in the range of 100-1400 ° C. Gallium vapors are in contact with ammonia in the second zone. As a result of the reaction of gallium gas with ammonia, single crystals or epitaxial GaN layers grow on the substrate.

The method according to the invention makes it possible to obtain single crystals or epitaxial layers of gallium nitride from the simplest substrates and without significant technological problems. The process does not require expensive and complicated equipment - the simplest, typical devices are used.

The method according to the invention is presented in more detail in the application examples. The diagram of an exemplary device is presented in the figure.

Example 1.

5g of gallium was placed in a furnace 1 in a vessel 2 positioned in a horizontal pipe 3 supplied with nitrogen flowing at a rate of 8 cm / s. The temperature in the first heating zone was 850 ° C. A stream of ammonia was supplied through inlet 4 at a rate of 0.5 cm / sec. A substrate 5 made of silicon nitride was placed in the second zone of the furnace and maintained at 1100 ° C. Under these conditions, needle-shaped GaN single crystals with dimensions of 4 x 0.2 mm grow during 6h on the substrate 5.

Example 2.

5 g of metallic gallium was placed in a vessel 2 positioned in a horizontal tube 3 in a stream of argon flowing at a rate of 5 cm / s, the temperature in the first heating zone being 1000 ° C. Under these conditions, a monocrystalline GaN layer 0.5 mm thick was growing on the monocrystalline aluminum trioxide substrate 5 located in the second zone of the furnace at the temperature of 1050 ° C during 5 hours. The flow rate of ammonia in the reactor was 0.75 cm / s.

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Zone I - \, - Zone II

Publishing Department of the UP RP. Mintage 50 copies Price PLN 2.00.

Claims (1)

Patent claim A method of producing gallium nitride single crystals and epitaxial layers by reacting gallium with ammonia, characterized by placing gallium in the first zone of the furnace in a vessel in a pipe fed with a carrier gas such as N2, H2 or an inert gas such as Ar or He, at a rate of 0.1-20 cm / s, at a temperature of 100-1400 ° C, then gallium vapor is transferred by means of a carrier gas to the second zone of the furnace, where a substrate made of silicon nitride, silicon carbide is placed or aluminum trioxide, and fed with a stream of ammonia at a rate of 0.1-20 cm / sec, while the temperature in the second zone of the furnace is kept at 100-1400 ° C.