Wei Xuecheng

Influence of growth conditions on the V-defects in InGaN/GaN MQWs

The influence of the growth temperature, TMIn/TEGa and V/III ratio on the V-defects of InGaN/GaN multi-quantum wells (MQWs) has been investigated and discussed. When the TMIn flow increases from 180 to 200 sccm, the density of V-defects increases from 2.72 × 1018 to 5.24 × 1018 cm−2, and the V-defect width and depth increase too. The density also increases with the growth temperature. The densities are 2.05 × 108, 2.72 × 1018 and 4.23 × 108 cm−2, corresponding to a growth temperature of 748, 753 and 758 °C respectively. When the NH3 flows are 5000, 6600 and 8000 sccm, the densities of the V-defects of these samples are 6.34 × 1018, 2.72 × 1018 and 4.13 × 1018 cm−2, respectively. A proper V/III ratio is needed to achieve step flow growth mode. We get the best quality of InGaN/GaN MQWs at a growth temperature of 753 °C TMIn flow at 180 sccm, NH3 flow at 6600 sccm, a flatter surface and less V-defects density. The depths of these V-defects are from 10 to 30 nm, and the widths are from 100 to 200 nm. In order to suppress the influence of V-defects on reverse current and electro-static discharge of LEDs, it is essential to grow thicker p-GaN to fill the V-defects.