Growth reactor for gallium-nitride crystals using ammonia and hydrogen chloride
The present invention in one preferred embodiment discloses a new design of HVPE reactor, which can grow gallium nitride for more than one day without interruption. To avoid clogging in the exhaust system, a second reactor chamber is added after a main reactor where GaN is produced. The second reactor chamber may be configured to enhance ammonium chloride formation, and the powder may be collected efficiently in it. To avoid ammonium chloride formation in the main reactor, the connection between the main reactor and the second reaction chamber can be maintained at elevated temperature. In addition, the second reactor chamber may have two or more exhaust lines. If one exhaust line becomes clogged with powder, the valve for an alternative exhaust line may open and the valve for the clogged line may be closed to avoid overpressuring the system. The quartz-made main reactor may have e.g. a pyrolytic boron nitride liner to collect polycrystalline gallium nitride efficiently. The new HYPE reactor which can grow gallium nitride crystals for more than 1 day may produce enough source material for ammonothermal growth. Single crystalline gallium nitride and polycrystalline gallium nitride from the HYPE reactor may be used as seed crystals and a nutrient for ammonothermal group III-nitride growth.
1. A hydride vapor phase epitaxy reactor for growing a group III-nitride crystalline material, comprising
(a) a reactor body formed of a material compatible with reactants for growing the group III-nitride crystalline material;
(b) a first gas inlet for introducing a first reactant comprising a halide gas;
(c) a second gas inlet for introducing a second reactant comprising ammonia;
(d) a stand in a first reactor zone in a chamber of the reactor body to hold a substrate upon which the group III-nitride crystalline material is grown;
(e) a transition zone downstream of the stand;
(f) a second reactor zone downstream of the transition zone; and
(g) one or more heaters positioned and configured to heat the first reaction zone and the transition zone but not the second reactor zone chamber to a temperature above the precipitation temperature of ammonium halide, such that the ammonium halide precipitates in the second reactor zone during operation; and
(h) wherein the reactor has a removable liner for growing polycrystalline group III-nitride material in and removing said polycrystalline group III-nitride material from the reactor.
2. A hydride vapor phase epitaxy reactor according to claim 1 wherein the removable liner comprises pyrolytic boron nitride.
3. A hydride vapor phase epitaxy reactor according to claim 1 wherein the second reactor zone has a cross-sectional area in a direction of gas flow that is sufficiently large to allow precipitated ammonium halide to settle and form a depleted exhaust gas.
4. A hydride vapor phase epitaxy reactor according to claim 1 wherein the second reactor zone has a reservoir sufficiently large to collect settled precipitated ammonium halide.
5. The reactor of claim 4 , wherein the reservoir has more than one isolation valve.
6. The reactor of claim 5 , wherein overpressure of the reservoir is avoided by automatic switching of the isolation valves.
7. The reactor of claim 4 , wherein the reactor has plural plates with openings located between the first reactor zone and a reservoir of the second reactor zone, the openings of the plates are offset to not provide a direct optical path from the first reactor zone to said reservoir, and the plates are located in a position where the temperature is between 300° C. to 700° C. in operation.
8. A hydride vapor phase epitaxy reactor for growing a group III-nitride crystalline material, comprising
(a) a reactor body formed of a material compatible with reactants for growing the group III-nitride crystalline material;
(b) a first gas inlet for introducing a first reactant comprising a halide gas;
(c) a second gas inlet for introducing a second reactant comprising ammonia;
(d) a stand in a first reactor zone in a chamber of the reactor body to hold a substrate upon which the group III-nitride crystalline material is grown;
(e) a transition zone downstream of the stand;
(f) a second reactor zone downstream of the transition zone; and
(g) one or more heaters positioned and configured to heat the first reaction zone and the transition zone but not the second reactor zone to a temperature above the precipitation temperature of ammonium halide, such that the ammonium halide precipitates in the second reactor zone during operation; and wherein
(h) the first reactor zone is constructed with a quartz tube,
(i) the second reactor zone has a reservoir constructed as a metal chamber,
(j) the quartz tube and the metal chamber are connected with an O-ring-sealed flange,
(k) the location of the O-ring of the sealed flange is separated from the waste gas stream by a sufficient distance that the temperature of a wall at the O-ring-sealed flange and touching the waste gas stream is maintained higher than 200° C. in operation.
9. The reactor of claim 8 , wherein the O-ring of the sealed flange is separated from the waste gas stream by a sufficient distance that the temperature of the wall at the O-ring-sealed flange and touching the waste gas stream is maintained higher than 350° C. in operation.
10. The reactor of claim 8 , wherein the O-ring of the sealed flange is cooled with air or fluid.