Photoluminescence and Infrared Absorption Study of Isoelectronic Impurity Passivation by Hydrogen
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Photoluminescence and Infrared Absorption Study of Isoelectronic Impurity Passivation by Hydrogen
M. Capizzi, A. Polimeni, G. Baldassarri Högher von Höghersthal, M. Bissiri, A. Amore Bonapasta1, F. Jiang2, M. Stavola2, M. Fischer3, A. Forchel3, I.K. Sou4 and W.K. Ge4 INFM and Dipartimento di Fisica, Univ. di Roma, P.le A. Moro 2, I-00185 Roma, Italy 1 ICMAT-CNR, Via Salaria Km 29,300 - C.P 10 - 00016 Monterotondo Stazione Roma, Italy 2 Dept. of Physics, Lehigh University, Bethlehem, Pennsylvania 18015, USA 3 Universität Würzburg, Technische Physik, Am Hubland 97074 Würzburg, Germany 4 Department of Physics, Hong Kong University, Kowloon, China
ABSTRACT
The effects of H irradiation and thermal annealing on the optical properties of (InGa)(AsN) heterostructures have been investigated by photoluminescence (PL) and infrared absorption, as well as by theoretical methods. It has been found that different N clusters contribute to the band gap red-shift reported for (InGa)(AsN) alloys, with a sizable localization of the carrier wavefunctions around N atoms. Infrared absorption measurements indicate that two different NH complexes are formed, whose vibrational frequencies are in good agreement with theoretical estimates. The ability of hydrogen to passivate different isoelectronic impurities is confirmed by PL results in H irradiated Zn(STe).
INTRODUCTION
Atomic hydrogen is unintentionally introduced by modern growth techniques and processing into elemental and compound semiconductors where H diffuses easily, forms chemical complexes with acceptors, donors, and deep defects thus altering the optical and transport properties of the host crystals [1]. It is not obvious that this picture should hold when the valences of both the impurity and the host atoms are satisfied by full bonds, as for isoelectronic impurities. Nitrogen is an isoelectronic impurity of technological interest in (InGa)As, whose electronic properties are dramatically affected by N introduction because of the large difference between N electronegativity and/or size and those of the replaced As atom. In particular, a giant reduction of the band gap energy has been reported for N concentration of the order of a few percent with a parallel increase in the electron effective mass [2,3]. These effects have been explained in terms of an interaction between N levels and the conduction band states of the host lattice [4,5]. Recently, our group has shown that hydrogen irradiation of InxGa1-xAs1-yNy fully passivates N, independent of its concentration, and restores the optical properties of (InGa)As [6,7]. In particular, i) in the dilute limit (y ≤ 0.001), N photoluminescence (PL) lines due to exciton F9.4.1 Downloaded from https://www.cambridge.org/core. Columbia University - Law Library, on 06 Aug 2019 at 00:45:52, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/PROC-719-F9.4
recombination at N-related complexes are fully quenched upon hydrogenation [6]; ii) in the alloy limit (y ≥ 0.01), t
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