| 摘要 |
A III-V transistor 1, for example a HEMT, includes an etch-stop layer 11 which comprises both aluminium and phosphorous. The presence of aluminium allows a dry etch chemistry to be effective and the presence of phosphorous allows a wet etch chemistry to be effective, so that either chemistry can be selected depending on precise device characteristics required. An ohmic contact layer 10 is formed on the semiconductor channel layer 4, where the bottom of the ohmic contact layer comprises the etch stop layer, which defines the shape of the gate recess at its junction with the channel layer. A stepped recess 13 may be formed, through several etch stop layers within the ohmic contact layer 10. |
