III‐Nitride Quantum Dots for Optoelectronic Devices

Molecular beam epitaxial growth and the properties of InGaN/GaN self‐assembled quantum dots have been investigated in detail. The quantum dots, emitting in the visible range, have been studied optically through temperature‐dependent, excitation‐dependent, and time‐resolved photoluminescence. The density of the quantum dots is found to increase from 7 × 10
⁷
 cm
⁻²
on the first layer to ∼5 × 10
¹⁰
 cm
⁻²
on subsequent layers. The dot height follows a similar trend, increasing from 3 to 5 nm, while the base width of the quantum dots is relatively fixed. The performance characteristics of all quantum dot converter white light‐emitting diodes with blue‐ and red‐emitting dots are described. Red‐emitting quantum dot lasers, emitting at up to 630 nm, have been realized. They are characterized by relatively low threshold current densities (1.6 kA cm
⁻²
) and high temperature stability (
T

₀
 ∼ 240 K). The maximum measured output power is 30 mW. Dynamic characterization of the lasers has also been performed, from which a maximum small signal modulation bandwidth of 2.4 GHz has been measured.