Deep-Level Defects in MBE-Grown GaN-Based Laser Structure

T. Tsarova a, T. Wosiński a, A. Mąkosa a, C. Skierbiszewski b, I. Grzegory b and P. Perlin b a Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland b Institute of High Pressure Physics“Unipress”, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland

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Received: 9 06 2007;

We present results of deep-level transient spectroscopy investigations of defects in a GaN-based heterostructure of a blue-violet laser diode, grown by plasma-assisted molecular beam epitaxy on a bulk GaN substrate. Three majority-carrier traps, T1 at EC - 0.28 eV, T2 at EC - 0.60 eV, and T3 at EV + 0.33 eV, were revealed in deep-level transient spectra measured under reverse-bias conditions. On the other hand, deep-level transient spectroscopy measurements performed under injection conditions, revealed one minority-carrier trap, T4, with the activation energy of 0.20 eV. The three majority-carrier traps were revealed in the spectra measured under different reverse-bias conditions, suggesting that they are present in various parts of the laser-diode heterostructure. In addition, these traps represent different charge-carrier capture behaviours. The T1 trap, which exhibits logarithmic capture kinetics, is tentatively attributed to electron states of dislocations in the n-type wave-guiding layer of the structure. In contrast, the T2, T3, and T4 traps display exponential capture kinetics and are assigned to point defects.

DOI: 10.12693/APhysPolA.112.331 PACS numbers: 71.55.Eq, 73.20.Hb, 61.72.Lk, 81.15.Hi