Tunable spectral response of a Ga(AsN) superlattice diode by post-growth hydrogenation and thermal annealing N. Balakrishnan, 1 * G. Pettinari, 2 A. Patanè, 1 * O. Makarovsky, 1 and M. Hopkinson 3 1 School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom 2 National Research Council (CNR), Institute for Photonics and Nanotechnologies (IFN- CNR), via Cineto Romano 42, 00156 Roma, Italy 3 Department of Electronic and Electrical Engineering, University of Sheffield, S3 3JD Sheffield, United Kingdom *Corresponding authors: ppxnb3@nottingham.ac.uk; amalia.patane@nottingham.ac.uk The nitrogen-induced band gap reduction in III-V semiconductor compounds is a remarkable physical phenomenon in condensed matter physics and makes dilute nitride III-N- V alloys promising candidates for several applications, including nanophotonics and photovoltaics [1-2]. Even more remarkable is the combined effect of N and H atoms. The incorporation of hydrogen in III-N-Vs tends to passivate the electronic activity of nitrogen through the formation of N-H complexes. Hydrogenation combined with lithography and masking of an optically active dilute nitride III-N-V alloy has been used to fabricate ordered arrays of zero-dimensional nanostructures and site-controlled single photon emitters [1]. Hydrogenation and laser excitation of a III-N-V also provide a versatile top-down approach to band gap profiling [3-4]. To date, the N passivation by H and/or dissociation of N-H complexes have been examined in III-N-V epilayers and quantum wells grown just below (< 100 nm) the surface, but never implemented and demonstrated in a device structure where the active region is embedded deep below the surface and incorporated between doped contact layers. In this work, we show that the spectral response of a Ga(AsN)/AlAs superlattice (SL) p- i-n diode can be tuned by post-growth hydrogen irradiation and thermal annealing. By the controlled diffusion of hydrogen and thermal dissociation of the N-H complexes, we can finely tune both the photocurrent absorption and electroluminescence (EL) emission energy of the SL. A focused laser beam is also used to diffuse hydrogen from the p-type GaAs layer towards the SL. Near band-edge states created by this process provide preferential channels for the electrical injection of carriers into the SL and activates nanoscale light emitting regions. Thus, post- growth hydrogenation can provide an effective route to the fabrication of photonic devices and optical integrated circuits with distinct, tailor- made light absorbing regions, all integrated onto a single substrate. Opportunities for realizing a movable nano-LED are also presented [5]. [1] S. Birindelli et al., Nano Lett. 14, 1275 (2014). [2] R. Trotta et al., Adv. Funct. Mater. 22, 1782 (2012). [3] N. Balakrishnan et al., Appl. Phys. Lett. 99, 021105 (2011). [4] N. Balakrishnan et al., Phys. Rev. B 86, 155307 (2012). [5] N. Balakrishnan et al., unpublished (2014); G. Pettinari et al., Appl. Phys. Lett 103, 241105 (2013). Figure: (a) EL spectra at I = 8 mA and T = 296 K for a hydrogenated Ga(AsN)/AlAs SL. Spectra were measured following a thermal annealing at T a = 300 C at different time t a . (b) μEL maps at T = 10 K, 100 K and 160 K of the laser activated nanoscale light emitting area. 1.3 1.4 1.5 Virgin 12 h 3h 2h 1h EL Intensity (arb.u) Energy (eV) t a =0 6h T a = 300 o C (b) T = 10 K T = 100 K 1 µm (a) T = 160 K B-O-7 12:15, 10/07/2014, Pennine Lecture Theatre 73 View publication stats View publication stats