Dislocation density dependence of stimulated emission characteristics in AlGaN/Al multiquantum wells

Abstract

We investigated dislocation density dependence on stimulated emission characteristics of AlGaN/AlN multiquantum wells (MQWs: emission wavelength of approximately 285 nm) on AlN templates with various dislocation densities. We found that the stimulated emission characteristics of the deep UV MQWs were strongly dependent on the dislocation densities. A reduction of the dislocation densities is very important in order to realize good stimulated emission characteristics of deep UV MQWs. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Ultraviolet-B band lasers fabricated on highly relaxed thick Al0.55Ga0.45N films grown on various types of AlN wafers

“…32) In contrast, there are many reports on using a photoexcitation method as a low-threshold value of carriers as well required for laser oscillation. [33][34][35][36][37][38][39][40][41][42] In order to summarize these results, very low oscillation threshold power densities (several kilowatts per centimeter squared) are obtained for lasers in the UV-C region. On the other hand, most laser oscillation threshold power densities in the UV-B region are still as high as about several hundred kilowatts per centimeter squared.…”

Electrical properties of relaxed p-GaN/p-AlGaN superlattices and their application in ultraviolet-B light-emitting devices

“…A 10-nm-thick p-GaN was grown for electrical contact with the p-electrode. The n-electrode (VAlTiAu) and p-electrode (NiPtAu) were The AlN molar fraction of AlGaN and the thickness of the SL were determined by peak analysis by 2θ-ω scanning Xray diffraction (XRD) and reciprocal space map imaging around the (20)(21)(22)(23)(24) diffraction. The Al composition of the 12period p-GaN (8 nm)/p-Al 0.5 Ga 0.5 N (8 nm) SL was difficult to identify because of the split of the peaks in XRD reciprocal space mapping caused by relaxation during the growth of the SL.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] This is because the current density threshold is too high for laser oscillation to operate without breaking down in UVB or UVC LDs. [15][16][17][18][19][20][21][22][23][24][25] The lowest threshold for optically pumped stimulated emission in the UVB band is reported to be 56 kW cm −2 at 310 nm using a relaxed thick Al 0.6 Ga 0.4 N underlying layer without a p-type layer. 26) This means that a current density of at least 10 kA cm −2 , and usually more, is necessary for laser oscillation depending on the carrier injection efficiency and the light confinement efficiency.…”