Active region dimensionality and quantum efficiencies of InGaN LEDs from temperature dependent photoluminescence transients

Nuri Can; Serdal Okur; Morteza Monavarian; Fan Zhang; Vitaliy Avrutin; Hadis Morkoç; Ali Teke; Ümit Özgür

doi:10.1117/12.2179637

13 March 2015 Active region dimensionality and quantum efficiencies of InGaN LEDs from temperature dependent photoluminescence transients

Nuri Can, Serdal Okur, Morteza Monavarian, Fan Zhang, Vitaliy Avrutin, Hadis Morkoç, Ali Teke, Ümit Özgür

Author Affiliations +

Proceedings Volume 9363, Gallium Nitride Materials and Devices X; 93632U (2015) https://doi.org/10.1117/12.2179637
Event: SPIE OPTO, 2015, San Francisco, California, United States

Abstract

Temperature dependent recombination dynamics in c-plane InGaN light emitting diodes (LEDs) with different well thicknesses, 1.5, 2, and 3 nm, were investigated to determine the active region dimensionality and its effect on the internal quantum efficiencies. It was confirmed for all LEDs that the photoluminescence (PL) transients are governed by radiative recombination at low temperatures while nonradiative recombination dominates at room temperature. At photoexcited carrier densities of 3 – 4.5 x 10¹⁶ cm^-3, the room-temperature Shockley-Read-Hall (A) and the bimolecular (B) recombination coefficients (A, B) were deduced to be (9.2x10⁷ s^-1, 8.8x10^-10 cm³s^-1), (8.5x10⁷ s^-1, 6.6x10^-10cm³s^-1), and (6.5x10⁷ s^-1, 1.4x10^-10 cm³s^-1) for the six period 1.5, 2, and 3 nm well-width LEDs, respectively. From the temperature dependence of the radiative lifetimes, τ_rad α T^n/2, the dimensionality n of the active region was found to decrease consistently with decreasing well width. The 3 nm wide wells exhibited ~T^1.5 dependence, suggesting a three-dimensional nature, whereas the 1.5 nm wells were confirmed to be two-dimensional (~T¹) and the 2 nm wells close to being two-dimensional. We demonstrate that a combination of temperature dependent PL and time-resolved PL techniques can be used to evaluate the dimensionality as well as the quantum efficiencies of the LED active regions for a better understanding of the relationship between active-region design and the efficiency limiting processes in InGaN LEDs.

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Nuri Can, Serdal Okur, Morteza Monavarian, Fan Zhang, Vitaliy Avrutin, Hadis Morkoç, Ali Teke, and Ümit Özgür "Active region dimensionality and quantum efficiencies of InGaN LEDs from temperature dependent photoluminescence transients", Proc. SPIE 9363, Gallium Nitride Materials and Devices X, 93632U (13 March 2015); https://doi.org/10.1117/12.2179637

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