K. Wolter

Finite interface effects for thin GaInAs/InP quantum wells grown by LP-MOVPE with a growth interruption sequence

Abstract A prerequisite for growing quantum wells at the industrial level is to control the interface roughness. This is a dominant problem for very thin films and, in this respect, growth interruption sequences have been proposed. In this work, we investigate the interface layers, produced between two InP barriers, by a growth interruption sequence of 8 s: 6 s are under phosphine and 4 s under arsine. We find the resulting build-up of ultrathin (∼ 2 MLs thick) layers of InAsP, strained between the two limiting barriers.

Interface characterization of strained InGaAs/InP quantum wells after a growth interruption sequence

Abstract We have analyzed ultrathin (5–10 monolayers) In 1− x Ga x As / InP (0.17 ≤ x ≤ 1) quantum wells grown by low-pressure metalorgan vapour phase epitaxy using optical spectroscopy and transmission electron microscopy. We find, for all compositions, evidence for a complex interface structure at both the lower and the upper interface. Both originate from interdiffusion of arsenic and phosphorus at growth time. The influence of the interface structure on the optical transition energies is discussed in detail.

Interface Properties of Strained InGaAs/InP Quantum Wells Grown by LP-MOVPE

We have analysed ultrathin (5-10 monolayers) In1-xGaxAs/InP (0.17 < x > 1) quantum wells grown by low-pressure metal organic vapour phase epitaxy using optical spectroscopy and transmission electron microscopy. We find, for all compositions, evidence for a complex interface structure at both the lower and the upper interface. Both originate from interdiffusion of arsenic and phosphorus at growth time. The influence of the interface structure on the optical transition energies is discussed in detail.

Optical characterization of strained InGaAs/InP quantum well structures

The effects of strain on the optical properties of In 1-x Ga x As/InP multiple-quantum well structures grown by low pressure metal organic vapor phase epitaxy have been investigated by photoluminescence spectroscopy. The investigated composition range is varied between 0.17 ? x Ga ? 1.00. Sputtered neutrals mass spectrometry has been used to calibrate the growth interpolated nominal compositions. Distinct peaks from monolayer variations of well thickness are observed from all samples. The analysis of the PL-spectra leads to the assumption of an intermediate layer of InAs 0.65 P 0.35 at the InP to In 1=x Ga x As (lower) interface.

Evidence for non-uniform interface thickness in strained InGaAs/InP quantum wells

Abstract Advanced materials for optoelectronic device production increasingly use ultrathin (a few monolayers thick) quantum wells of InGaAs lattice matched to InP. For instance, in the particular case of optical fiber communications using wavelengths of 1.3 μm, the standard requirement is to grow active layers about 8 monolayers thick, with abrupt interfaces and good uniformity across a 2 in wafer. In this case, to combine mass production techniques with a high degree of integration, low-pressure, metallo-organic vapor phase epitaxy (LP-MOVPE) seems to be the most promising technique. However, because LP-MOVPE is very sensitive to the gas switching and growth interruption sequences, finite interface layers develop and modify the optical properties of the devices. In this work, we demonstrate that such interfaces are not uniform but depend on the initial degree of coverage with foreign species. In the particular case of InP/InGaAs, we find that the typical dispersion (for a given series of samples) is of the order of 0.5 Langmuir.

Interface properties of strained InGaAs/InP quantum wells grown by low pressure, metallo-organic vapour phase epitaxy

We have analysed the interface structure of ultrathin (5–10 monolayers) In1 − x GaxAs/InP (0.17 ⩽ x ⩽ 1) quantum wells grown by low pressure, metallo-organic vapour phase epitaxy, using optical spectroscopy and transmission electron microscopy. For all compositions, we find evidence for a complex interface structure originating from intermixing of arsenic and phosphorus during growth. The effect of the interface structure on the optical transition energies is compared with calculations based on the envelope function model.

Growth and characterization of In0.53Ga0.47As/InxGa1−xAs strained-layer superlattices

Abstract Since the early proposal that InGaAs/InGaAs strained-layer superlattices (SLSs) should constitute a new class of optoelectronic materials, very little work has been done to master the growth conditions and optimize the resulting superlattice properties. In this work, we present the results of a preliminary investigation of SLSs grown by low-pressure metal-organic vapour phase epitaxy. Two different series of samples were grown to check independently the effect of well thickness and barrier composition. In both cases, in order to conserve one layer nominally lattice-matched to InP, the wells had a standard composition In0.53Ga0.47As.

Type-I and type-II Wannier-Stark effect in InGaAs/InGaAs superlattices

The formation of minibands is demonstrated in photocurrent experiments on shallow In0.53Ga0.47As/In0.40Ga0.60 As superlattices grown by low-pressure metal-organic vapor-phase epitaxy. Field-dependent variations of the spectral shape are attributed to Wanner-Stark localization. Both type-I transitions between electrons and heavy holes and type-II transitions involving light holes confined in the In0.40Ga0.60 As layers are observed and distinguished by their characteristic field dependence.

Electro-Optic Characterization of InGaAs/InP MQW p-i-n Modulator Structures

For self electro-optic effect device applications, multiple quantum well modulator devices in the material system InGaAs/InP are studied. The applied experimental techniques are differential electrotransmission and photoluminescence with and without electric field. The optoelectronic properties of the modulators, including transport and recombination processes, are studied in the experiments. The theory describes the electric field dependence of respectively the confined state energies, overlap of electron-hole wavefunctions, the dielectric constants ϵ1 and ϵ of the multiple quantum well material and the differential electrotransmission spectra.

Optical characterization of indium-rich strained In1−xGaxAs/InP single- and multiple-quantum-well structures

Abstract We report on the photoluminescence spectroscopy of a large set of strained In 1− x Ga x As/InP quantum well structures grown by low pressure metallo-organic vapour phase epitaxy. Distinct peaks from monolayer steps are observed in all samples. For the first time, data on indium-rich In 1− x Ga x As/InP structures with complementary gallium contents as low as x Ga = 0.07 and x Ga = 0.11 are reported. The sample quality appears independent of the number of quantum wells stacked in the structure. With decreasing gallium content, a decrease in luminescence intensity is observed, which is related to an increase in the number of non-radiative recombination centres with respect to lattice-matched samples.