Experimental and modelling study of InGaBiAs InP alloys with up to 5.8% Bi, and with Δso > Eg

• Published in: Semiconductor science and technology Vol. 30; no. 9
• Main Authors: Chai, Grace M T, Broderick, C A, O'Reilly, E P, Othaman, Z, Jin, S R, Petropoulos, J P, Zhong, Y, Dongmo, P B, Zide, J M O, Sweeney, S J, Hosea, T J C
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.09.2015
• Subjects: bismides; InGaBiAs alloys; photo-modulated reflectance; spin-orbit splitting; valence band anti-crossing
• ISSN: 0268-1242; 1361-6641
• DOI: 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 Δso 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 m), while Δso increases from 0.42 to 0.62 eV, leading to a crossover between Eg and Δso around 3.8% Bi. The 5.8% Bi sample is the first example of this alloy where Δso > Eg has been confirmed at all temperatures. The condition Δso > 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 Δso 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.