Barrier-confinement-controlled carrier transport into quantum wires

By using subpicosecond laser light pulses with a polarization perpendicular to deep etched ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As/InP quantum wires, initial spatial electron-hole distributions have been prepared that are predominantly located in the unpatterned InP buffer layer. Under these excitation conditions the photoluminescence rise time increases significantly with decreasing wire width from about 25 ps for a two-dimensional unetched reference structure to about 150 ps for 34-nm-wide wires. Temperature-dependent studies of the rise times indicate the existence of an effective barrier in the InP regions of the quantum wires. From detailed calculations of the electronic states, which extend from the unpatterned InP buffer into the quantum wires, we show that confinement effects in the InP barriers control the carrier transport from the buffer into the ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As wire.