InGaN-based blue laser diodes

Abstract

The continuous-wave (CW) operation of InGaN multiquantum-well (MQW) structure laser diodes (LDs) was demonstrated at room temperature (RT) with a lifetime of 100 h. The threshold current and the voltage of the LDs were 50 mA and 5 V, respectively. The threshold current density was 8.8 kA/cm/sup 2/. The carrier lifetime and the threshold carrier density were estimated to be 3.5 ns and 1.8/spl times/10/sup 20//cm/sup 3/, respectively. The Stokes shift of the energy difference between the absorption and the emission energy of the InGaN MQW LD's were 140 meV. Both spontaneous and stimulated emission of the LD's originated from this deep localized energy state which is equivalent to a quantum dot-like state. From the measurements of gain spectra and an external differential quantum efficiency dependence on the cavity length, the differential gain coefficient, the transparent carrier density, threshold gain and internal loss were estimated to be 5.8/spl times/10/sup -17/ cm/sup 2/, 9.3/spl times/10/sup 19/ cm/sup -3/, 5200 cm/sup -1/, and 43 cm/sup -1/ respectively.