Method for preparing raw material for vapor-method aluminum nitride crystal growth

Abstract

The invention discloses a method for preparing a raw material for vapor-method aluminum nitride crystal growth. The method comprises the specific steps of soaking a tungsten crucible and a crucible cover which are required to be used in aqua regia for 30-120 minutes, taking out the tungsten crucible and the crucible cover, cleanly flushing, and drying for later use; adding aluminum nitride powder into the tungsten crucible, and carrying out multi-layer compacting treatment; covering the tungsten crucible with the crucible cover, putting in a tungsten-mesh heating furnace, vacuumizing until the pressure is 1*10<-3>Pa, inflating with high-purity nitrogen gas until the pressure is 30kPa, heating to the temperature of 300 DEG C, keeping the temperature constant for 1 hour, heating to the temperature of 800 DEG C, and keeping the temperature constant for 1 hour; inflating the tungsten-mesh heating furnace with high-purity nitrogen gas until the pressure is 50kPa, heating to the temperature of 1800 DEG C, keeping the temperature constant for 5 hours, heating to the temperature of 2,050 DEG C, and keeping the temperature constant for 8 hours; cooling to room temperature, thereby obtaining an aluminum nitride sinter cake which serves as the raw material for vapor-method aluminum nitride crystal growth. According to the method, a compact sintered body is prepared from the aluminum nitride powder, so as to control vapor-phase reaction, thus the requirements of RVT (Physical Vapor Transport)-method aluminum nitride crystal material growth for raw materials are met.

Description

technical field [0001] The invention relates to a method for preparing raw materials for growing aluminum nitride crystals by a vapor phase method. Background technique [0002] Aluminum nitride single crystal material is an ideal substrate material for the development of new high-power microwave devices and short-wavelength optoelectronic devices, but it is still difficult to obtain aluminum nitride single crystal material. The theoretically calculated melting point of aluminum nitride is 2800°C, and the dissociation pressure is 20MPa. Therefore, it is difficult to grow single crystals by melt Czochralski method or temperature gradient solidification method like silicon and gallium arsenide. One of the more promising methods at present is the PVT (Physical Vapor Transport, physical vapor transport) method. The PVT growth principle of aluminum nitride is to sublimate and decompose high-purity aluminum nitride powder at the high-temperature source region, and condense at the...

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Problems solved by technology

Carbon is also a common impurity in aluminum nitride raw materials. The graphite heating materials and insulation materials used in the usual heating process can easily lead to carbon contamination.

In addition, because the aluminum nitride powder is spherical and has a high specific surface area, in the process of sublimation decomposition, the reaction speed is fast and it is difficult to control

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