Investigations on the effect of arsenic and phosphorus atomic exchange on the origin of crystal potential fluctuations in InAsP/InP epilayers

• Published in: Applied surface science 2025-02, Vol.682, p.161627, Article 161627
• Main Authors: Vashisht, Geetanjali, Roychowdhury, R., Rajput, P., Kumar, R., Trivedi, A., Balal, M., Bose, A., Tiwari, M.K., Barman, S.R., Sharma, T.K., Dixit, V.K.
• Format: Article
• Language: English
• Subjects: Anion exchange; InAsP/InP; Interdiffusion; MOVPE; Optoelectronics; S-shape; Strain
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.161627

The percolation of arsenic and phosphorus in the InAsP epilayer depends on various factors, such as gas-phase diffusion coefficients, surface reaction rates, misfit strain energy, bond energy, segregations, and the presence of defects and dislocations. The local structure of epilayer is thus affected by such redistribution of the ad-atoms that creates residual strain in the structures. Impact of the residual strain on the vibrational modes and the changes in the local crystal structure at the surface and interface regimes of the InAsP/InP structure are determined by x-ray photoelectron and extended x-ray absorption fine structure based analysis. Such local crystal fluctuations lead to the creation of two different potential minima in the energy band structure. The magnitude of these potential minima strongly depends on the strain states associated with the layer thickness. Thus, by controlling the strain states associated with the energetics and kinetics of ad-atoms like arsenic/phosphorus and layer thickness, “S” shaped excitonic peak energy luminescence nature can be controlled which affects the performance of optoelectronic and quantum spintronic devices based on the technologically important InAsP material system. [Display omitted] •The study investigates the origin of "S" shaped dependence of excitonic peak energy in MOVPE grown InAsP/InP structures.•Arsenic percolation at the phosphorus' desorption sites create residual strain in the InAsP/InP epilayer structures.•The presence of disorder/defect changes the local crystal structure at the surface and interface regimes.•It lead to the creation of local potential minima, whose magnitude strongly depends on the strain states.•Thus by controlling the strain states, "S" shaped dependence can be controlled in InAsP/InP material system. The study investigates the anion exchange mechanism between the ad-atoms of arsenic and phosphorus followed by their inter-diffusion processes, in InAsP/InP hetero-structures grown by metal organic vapor phase epitaxy technique. The energetics and kinetics of the ad-atoms like arsenic and phosphorus are governed by the growth conditions. It has been found that the percolation of arsenic and phosphorus in the epilayer depends on various factors, such as gas-phase diffusion coefficients, surface reaction rates, misfit strain energy, bond energy, segregations, and the presence of defects and dislocations. Effects of anion exchange mechanisms on generating local crystal potential