Photoluminescence characterization of InGaP/GaAs heterostructures grown by metalorganic chemical vapor deposition

Abstract

Growth conditions of metalorganic chemical vapor deposition have been investigated for the purpose of obtaining abrupt InGaP/GaAs interfaces. Photoluminescence (PL) spectra of InGaP/GaAs quantum wells (QWs) are used to characterize these interfaces. The conventional gas switching sequence, i.e., simultaneously switching on group-III and -V gases, is found to provide only a broad peak at wavelengths longer than those of near-band-edge emissions from GaAs in the PL spectrum of the InGaP/GaAs QW. PL studies using QWs having an AlGaAs barrier, for example, AlGaAs/GaAs/InGaP and InGaP/GaAs/AlGaAs, show that the GaAs-on-InGaP interface is responsible for this broad peak. A novel gas switching sequence where group-III gas is switched on first results in sharp peaks corresponding to 5.7- and 2.8-nm-thick wells in the PL spectrum of InGaP/GaAs QW. Preflow of TMGa on InGaP surface is effective in suppressing the substitution of P atoms in InGaP to As atoms at the GaAs-on-InGaP interface.

Metalorganic chemical vapor deposition growth and characterization of InGaP/GaAs superlattices

“…The high-energy peak around 1.43 eV comes from GaAs and the low-energy peak around 1.38 eV comes from an ''unintentional'' InGaAsP interfacial layer. 2,4,8 We note that the low-energy peak dominates the spectrum, indicating that most of the carriers created by the external excitation are localized and recombine in the interface regions. The growth of sample 1b is quite similar to that of sample 1a except that half the AsH 3 flow rate is used to passivate the GaAs surface during the interruption.…”

“…By growing an additional GaP or a large-bandgap AlGaAs layer, the formation of the low-bandgap interface layer can be effectively suppressed. 3,4,7 In this paper, we show that under optimized growth conditions, indium surface segregation plays an important role in the formation of a low-bandgap interface layer in the growth of InGaP/ GaAs heterostructures.…”

“…Such unintentional interface layers often give rise to an additional photoluminescence (PL) peak below the bandgap energy of GaAs and suggest that this lattice-mismatched InGaAsP ''unintentional'' interface layer has a smaller bandgap. [2][3][4][5] Due to the smaller bandgap, this interface layer has been shown to have a strong effect on the electric transport and optical properties of the structures, and therefore these interface layers strongly affect the operation of the heterojunction device. In order to improve the performance of InGaP/GaAs-based devices, research on controlling the interface quality has been reported since the 1980s.…”

A study of GaInP/GaAs interfaces: metallurgical coupling of successive quantum wells

“…The GaAs-on-GaInP interface is then found to be quasi abrupt, taking into account a probably small memory effect or interdiffusion of P in the well responsible for the formation of an GaAsP-like layer and resulting in the small blue shift of Samples A and B. Nevertheless, no segregation into the GaAs well was observed, otherwise PL lines should have been red shifted, and no 'Q-line' [7] was detected. On the contrary, the 9 ML thick well in Sample C, which was the inverse interface, emitted at a significantly lower energy than the calculated prediction (1633 meV instead of 1682 meV).…”

“…Formation of abrupt interfaces has been investigated by optimization of switching sequences [6] to avoid compositional intermixing and then localized strains around the heterointerfaces. Recently, Nittono et al [7] have reported in GaInP/GaAs quantum wells grown by MOCVD that the GaAs-on-GaInP interface is responsible for a broad peak at a longer wavelength than GaAs gap (called 'Q-line') and therefore the disappearance of the QW peak in the photoluminescence spectrum. They have also shown that the GaInP-on-GaAs interface is responsible for the lowering of the quantum-well energy transition by about 30-50 meV.…”