Bonding of nitrogen in dilute InAsN and high In-content GaInAsN

Abstract

Dilute InAs(1-y)N(y) and high In-content Ga(1-x)In(x)As(1-y)N(y) layers with y lt = 0.012 and x gt= 0.92 were grown by rf-nitrogen plasma source molecular-beam epitaxy on InP substrates using a metamorphic GaInAs buffer layer. The bonding of nitrogen in these alloys was analyzed by Raman spectroscopy, showing that nitrogen is incorporated in dilute InAsN as isolated N(As) for a nitrogen content of y = 0.005; two additional nitrogen-related modes were found to appear at higher nitrogen contents (y=0.012), possibly due to the formation of higher-order di-nitrogen In-N complexes. The addition of a small amount of Ga to the InAsN ([Ga] lt = 8%) was found to lead to an almost complete change from pure In-N bonding to a preferential bonding of the substitutional nitrogen to at least one Ga neighbour. Further, the effect of nitrogen incorporation on the higher-lying E(ind 1) and E(ind 1) + delta(ind 1) interband transitions of InAsN has been studied by spectroscopic ellipsometry, revealing a high-energy shift of both interband transitions with increasing nitrogen content at a rate similar to that reported for dilute GaAsN

Structural and optical properties of dilute InAsN grown by molecular beam epitaxy

“…All four peaks are clearly seen in the difference spectrum. The modes at 402, 415, and 443 cm −1 were previously reported by Wagner et al 10 in Raman difference spectra of dilute InAsN epilayers with N = 1.2%.…”

“…Different N configurations may be involved in these two LVMs at 402 and 415 cm −1 . Wagner et al 10 tentatively assigned these peaks to In-N complexes of higher order involving nearest neighbor N-In-N vibrations ͑i.e., InN 2 As 2 complexes and higher orders͒. However, it should be noted that in the dilute alloy ͑N contents below 3%͒ the randomly distributed N atoms are located far away from each other within the crystal lattice ͑see discussion in Ref.…”

“…10,29 However, there is some ambiguity in the assignment of this band because it is usually revealed in difference spectra, and there are strong second-order optical modes from the InAs matrix in this frequency range. In order to confirm the origin of this feature, we performed FIR reflectivity measurements on InAsN/GaAs epilayers grown by MBE.…”

“…17 N-related local vibrational modes ͑LVMs͒ have been observed by Raman scattering in InAsN samples. 10 The observed LVMs were tentatively assigned to N As and to N-In-N complexes. Other N configurations involving nonsubstitutional N could yield important distortions of the lattice ͑i.e., strong deviations of Vegard's law͒.…”

N incorporation and photoluminescence in In-rich InGaAsN grown on InAs by liquid phase epitaxy

“…With 3 at% nitrogen, the material has been used for the fabrication of diode lasers emitting in the 1.3-1.55 µm optical communication range [6][7][8]. There are also a few reports on`high indium`InGaAsN with an In content > 50% and which is grown lattice-matched to InP substrates [9][10][11][12][13]. From theory, it has been established that nitrogen-induced band gap reduction in these materials occurs in a similar way to that in low indium content InGaAsN [14] and it exhibits some interesting phenomena, such as, weaker interaction between the nitrogen level and the conduction band as compared to that in low In content InGaAsN [10] and a change in nitrogen bonding configuration upon annealing [12].…”