Self-compensation effect in Si-doped Al0.55Ga0.45N layers for deep ultraviolet applications

The self-compensation effect in Si-doped Al0.55Ga0.45N layers was investigated using different SiH4/III ratios. The degree of compressive strain changed with SiH4 flow rate during growth. With a low SiH4/III ratio of 2.46 × 10−6, compressive strain was increased in comparison with the un-doped case. However, above this SiH4/III ratio, compressive strain decreased from xx = −5.07 × 10−3 to 4.28 × 10−3 when the ratio was increased to 4.1 × 10−5. For higher SiH4/III ratios, the compressive strain again increased, which is attributed to the self-compensation effect of Si atoms. A similar tendency was observed in Photo-luminescence (PL) results. While the UV-to-violet ratio (IUV/IVL) of room-temperature PL remained to be almost constant for SiH4/III ratios below 8.2 × 10−5, IUV/IVL decreased rapidly above this value, as a result of self-compensation of Si atoms. These results were in good agreement with the Hall effect measurements.