Estimation of Device Properties in AlGaInN-Based Laser Diodes by Time-Resolved Photoluminescence

Abstract

We estimated the optical characteristics of AlGaInN-based laser structures by time-resolved and standard photoluminescence. It was clarified that the microscopic distribution of the peak wavelength of GaInN active layers has a strong correlation with the threshold current and the slope efficiency. As an index representing the extent of this distribution, we used the depth in the tail states of the active layer, E 0 , for which we found an excellent correlation with the device properties. From an estimation of the external quantum efficiency as a function of equivalent cavity length, it was found that the sample with smaller E 0 has higher internal quantum efficiency and smaller internal absorption coefficient than those with larger E 0 .

Emission of biased green quantum wells in time and wavelength domain

“…A wavelength dependency of the carrier lifetime frequently observed in those experiments is usually explained by carrier localization. 20,21 From our experiments we would argue that stimulated emission is the reason for the wavelength dependent carrier lifetime.…”

Interdependency of surface morphology and wavelength fluctuations of indium‐rich InGaN/GaN quantum wells

“…One of the main challenges is to grow indium‐rich InGaN layers with good crystal quality 1. Homogeneous indium incorporation in the ternary InGaN QW layer is a key parameter to obtain highest peak gain and best laser results 2–4. Hence, it is necessary to gain a better understanding of InGaN growth mechanisms to optimize the QW growth to reach highest uniformity and lowest defect density.…”

Weak Carrier/Exciton Localization in InGaN Quantum Wells for Green Laser Diodes Fabricated on Semi-Polar {20\bar21} GaN Substrates

“…Such fluctuations form nanometerscale potential minima in InGaN QWs and create carrier localization centers. Although carrier localization centers improve internal quantum efficiencies (IQEs) for blue lightemitting diodes (LEDs), 10,11) it has been reported that a large localization energy deteriorates the threshold current and slope efficiency of LDs 12) and drastically reduces the photoluminescence (PL) intensity with dark spots in InGaN QWs in the green region. 13,14) Recently, Enya et al have reported 531 nm green lasing under pulsed operation, 15) and Yoshizumi et al have reported cw operation at 520 nm on novel semi-polar f20 21g GaN substrates.…”

“…Thus, the f20 21g plane appears suitable for green LDs with respect to the threshold current and slope efficiency. 12) Figure 3 shows (a) PL spectra and (b) the peak energy at 6 K as functions of excitation energy densities. The excitation energy densities were changed between 8.6 and 29,000 nJ/cm 2 , which correspond to a photogenerated carrier density from 1:7 Â 10 14 to 5:7 Â 10 17 cm À3 .…”