Effects of internal fields and potential inhomogeneity on the lasing properties of InGaN-based green laser diodes fabricated on (0001) polar substrates

摘要

The optical properties of InGaN-based green (512 nm) laser structures fabricated on (0001) GaN substrates are investigated by means of photoluminescence and gain spectroscopies. It is demonstrated that in the state-of-the-art (0001) green InGaN quantum wells, potential fluctuations are drastically suppressed, and the internal loss is as low as〜10 /cm, both of which lead to a low threshold current density of 2.75 kA/cm~2.The suppressed inhomogeneity also contributes to high linearity of gain increase with the injection current. The differential gain is relatively low, and is attributed to a low confinement factor in the longer wavelength spectral range.