Experimental and modelling study of InGaBiAs/InP alloys with up to 5.8% Bi, and with ∆(so) > E-g

• Main Authors: Chai, Grace M. T., Broderick, Christopher A., O'Reilly, Eoin P. O., Othaman, Zulkafli, Jin, Shirong, Petropoulos, J. P., Zhong, Yujun, Dongmo, Pernell B., Zide, Joshua M. O., Sweeney, Stephen J., Hosea, Thomas Jeff Cockburn
• Format: Article
• Published: Institute of Physics Publishing (IOP) 2015
• Subjects: QC Physics
• Online Access: http://eprints.utm.my/id/eprint/55151/; http://dx.doi.org/10.1088/0268-1242/30/9/094015

Temperature dependent photo-modulated reflectance is used to measure the band gap Eg and spin-orbit splitting energy ∆so in dilute-Bi In0.53Ga0.47As1-xBix/InP for 1.2% = x = 5.8%. At room temperature, Eg decreases with increasing Bi from 0.65 to 0.47 eV (~2.6 µm), while ∆so increases from 0.42 to 0.62 eV, leading to a crossover between Eg and ∆so around 3.8% Bi. The 5.8% Bi sample is the first example of this alloy where ∆so > Eg has been confirmed at all temperatures. The condition ∆so > Eg is important for suppressing hot-hole-producing non-radiative Auger recombination and inter-valence band absorption losses and so holds promise for the development of mid-infra-red devices based on this material system. The measured variations of Eg and ∆so as a function of Bi content at 300 K are compared to those calculated using a 12-band k.p Hamiltonian which includes valence band anti-crossing effects. The Eg results as a function of temperature are fitted with the Bose-Einstein model. We also look for evidence to support the prediction that Eg in dilute bismides may show a reduced temperature sensitivity, but find no clear indication of that.