1. Field
One or more embodiments herein relate to a semiconductor buffer structure, a semiconductor device including the semiconductor buffer structure, and a method of manufacturing the semiconductor buffer structure and the semiconductor device.
2. Description of the Related Art
Many nitride-based semiconductor devices use sapphire substrates that are expensive, hard to process, and have low electric conductivity. Also, when a sapphire substrate is epitaxially grown to a large size, the substrate may warp at high temperatures due to a low thermal conductivity. Consequently, it is difficult to make sapphire substrates large in size.
Semiconductor devices which use silicon substrates have been proposed in order to avoid some of these drawbacks. Because silicon has a higher thermal conductivity than sapphire, a substrate made of silicon will not bend as much even at temperatures required for growing nitride thin films. Accordingly, silicon substrates may be more suitable for making large devices that use nitride thin films.
However, the approach of using silicon substrates in nitride-based devices is not without drawbacks. For example, when a nitride buffer structure is grown on a silicon substrate, dislocation density may increase due to a mismatch in a gallium composition ratio between the substrate and the nitride buffer structure. This mismatch may promote the formation of cracks, which can compromise proper operation of the device or, in a worst case, render the device inoperative.