Physicochemical aspects of quantum dot array formation in the InAs/GaAs system by droplet epitaxy under MOVPE conditions

Self‐Assembled InAs Quantum Dots on InGaAsP/InP(100) by Modified Droplet Epitaxy in Metal–Organic Vapor Phase Epitaxy around the Telecom C‐Band for Quantum Photonic Applications

“…We attribute this to an out‐diffusion of indium and redistribution on the InGaAsP surface during the thermal ramp step which can lead to a reduction in droplet size and a “re‐wetting” of the surface. [ 35 ] As for the case of QDs on InGaAs, no long‐range etch pits around each QD are present. [ 12,13,15 ] From these observations, we can conclude that inserting the InGaAs(P) layers results in a modification of the growth kinetics from a mass‐transport regime (on bare InP) to a surface reaction‐limited regime on the interlayers, as previously suggested in our cross‐sectional tunneling microscopy (XSTM) study on InAs QDs on both InGaAs and InP [ 15 ] and predicted by Yoon et al [ 36 ] Although at the typical droplet temperature of 400 °C the In surface diffusion ρ apparently strongly differs for InGaAs and InGaAsP surfaces, with ρ InGaAs << ρ InGaAsP as discussed above (see also Figure 3 as reference) we observe that, after crystallization, QDs on both layers present a similar density of 1 × 10 10 cm −2 versus 2 × 10 10 cm −2 for InGaAs and InGaAsP, respectively (Figure 5c,d).…”