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Bulk GaN and AlGaN single crystals

Inactive Publication Date: 2005-07-28
FREIBERGER COMPOUND MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0016] According to one aspect of the invention, an extended Ga source is located within a reactor such that a portion of the Ga source is maintained at a relatively high temperature while most of the Ga source is maintained at a temperature close to, and just above, the melting temperature of Ga. In at least one embodiment of the invention, in order to obtain the desired temperature spread in the Ga source, a portion of the source tube extends outside of the reactor. Assuming the use of a modified HVPE process for the growth of the single crystal boule, preferably the high temperature is in the range of 450° C. to 850° C., and more preferably at a temperature of approximately 650° C., while the low temperature is less than 100° C. and preferably in the range of 30° C. to 40° C. As a result of this source configuration, the amount of Ga undergoing a reaction is controllable and limited, thus allowing extended growth cycles to be realized without experiencing degradation in the as-grown material.

Problems solved by technology

Although the high temperature of this zone allows high quality crystal growth, the growth rate at this temperature is relatively low.

Method used

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  • Bulk GaN and AlGaN single crystals
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  • Bulk GaN and AlGaN single crystals

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specific embodiments

Embodiment 1

[0056] According to this embodiment of the invention, the modified HVPE process described above was used to grow thick GaN layers on SiC substrates. Suitable GaN substrates were then fabricated and used in conjunction with the modified HVPE process of the invention to grow a GaN single crystal boule. The second GaN boule was cut into wafers suitable for device applications.

[0057] In this embodiment, multiple SiC substrates of a 6H polytype were loaded into the growth zone of a reactor similar to that shown in FIG. 1. The substrates were placed on a quartz sample holder with the (0001) Si on-axis surface positioned for GaN deposition. One kilogram of Ga metal was positioned in the source boat within the Ga source tube. After purging the reactor with Ar gas to remove air, the growth zone and the Ga source zone were heated to 1100° C. and 650° C., respectively. The majority of the Ga source, however, was maintained at a temperature of less than 100° C., typically in the r...

embodiment 2

[0068] In this embodiment, a GaN seed was first fabricated as described in Embodiment 1. The 5.08 centimeter diameter (i.e., 2 inch diameter) prepared GaN seed substrates were then placed within a stainless steel, resistively heated furnace and a GaN single crystal boule was grown using a sublimation technique. GaN powder, located within a graphite boat, was used as the Ga vapor source while NH3 gas was used as the nitrogen source. The GaN seed was kept at a temperature of 1100° C. during the growth. The GaN source was located below the seed at a temperature higher than the seed temperature. The growth was performed at a reduced pressure.

[0069] The growth rate using the above-described sublimation technique was approximately 0.5 millimeters per hour. After a growth cycle of 24 hours, a 12 millimeter thick boule was grown with a maximum boule diameter of 54 millimeters. The boule was divided into 30 wafers using a diamond wire saw and the slicing and processing procedures described ...

embodiment 3

[0070] In this embodiment, bulk GaN material was grown in an inert gas flow at atmospheric pressure utilizing the hot-wall, horizontal reactor described in Embodiment 1. Six 5.08 centimeter diameter (i.e., 2 inch diameter) silicon carbide substrates of a 6H polytype, were placed on a quartz pedestal and loaded into a growth zone of the quartz reactor. The substrates were located such that the (0001) Si on-axis surfaces were positioned for GaN deposition. Approximately 0.9 kilograms of Ga (7N) was located within a quartz boat in the Ga source zone of the reactor. This channel was used for delivery of gallium chloride to the growth zone of the reactor. A second quartz tube was used for ammonia (NH3) delivery to the growth zone. A third separate quartz tube was used for HCl gas delivery to the growth zone.

[0071] The reactor was filled with Ar gas, the Ar gas flow through the reactor being in the range of 1 to 25 liters per minute. The substrates were then heated in Ar flow to a temper...

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Abstract

Bulk GaN and AlGaN single crystal boules, preferably fabricated using a modified HVPE process, are provided. The single crystal boules typically have a volume in excess of 4 cubic centimeters with a minimum dimension of approximately 1 centimeter. If desired, the bulk material can be doped during growth, for example to achieve n-, i-, or p-type conductivity.

Description

CROSS-REFERENCES TO RELATED APPLICATION [0001] This application is a continuation-in-part of U.S. patent application Ser. No. 09 / 900,833, filed Jul. 6, 2001.FIELD OF THE INVENTION [0002] The present invention relates generally to semiconductor materials and, more particularly, to bulk single crystals. BACKGROUND OF THE INVENTION [0003] Recent results in the development of GaN-based light-emitting diodes (LEDs) and laser diodes (LDs) operating in the green, blue, and ultraviolet spectrum have demonstrated the tremendous scientific and commercial potential of group III nitride semiconductors (e.g., GaN, AIN, InN, and their alloys). These applications require electrically conducting substrates (e.g., GaN or AlGaN) so that a vertical device geometry can be utilized in which the electrodes are located on the top and bottom surfaces of the device structure. In addition to opto-electronic devices, group III nitride semiconductors can be used in a host of other applications such as communic...

Claims

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Application Information

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IPC IPC(8): C30B25/00
CPCC30B25/00C30B29/406C30B29/403C30B25/02C30B25/18
Inventor MELNIK, YURI V.SOUKHOVEEV, VITALIIVANTSOV, VLADIMIRTSVETKOV, KATIEDMITRIEV, VLADIMIR A.
Owner FREIBERGER COMPOUND MATERIALS
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