Naoteru Matsubara

Effects of Growth Temperature on Er-Related Photoluminescence in Er-Doped InP and GaAs Grown by Organometallic Vapor Phase Epitaxy with Tertiarybutylphosphine and Tertiarybutylarsine

The effects of growth temperature on Er-related photoluminescence (PL) have been investigated in Er-doped InP (InP:Er) and GaAs (GaAs:Er) grown by organometallic vapor phase epitaxy (OMVPE) using tertiarybutylphosphine (TBP) and tertiarybutylarsine (TBAs). In InP:Er, the PL spectra exhibit strong dependence on the growth temperature, and the intensity increases drastically in specimens prepared at temperatures lower than 550° C. Similar dependence of PL intensity on the growth temperature is observed in GaAs:Er. The activation energy obtained is about 3 eV in both materials. The activation energy is discussed based on atomic configurations of Er-related luminescence centers.

LOW-TEMPERATURE PHOTOLUMINESCENCE STUDY ON ER-DOPED GAP GROWN BY ORGANOMETALLIC VAPOR PHASE EPITAXY

Low-temperature photoluminescence spectra of Er-doped GaP grown by low-pressure organometallic vapor phase epitaxy was investigated under both above-band gap and below-band gap excitation conditions. Under all experimental conditions, similar Er-related spectra dominated by numerous sharp emission lines were obtained for the first time. The intensity dependence of the photoluminescence exhibits complicated behavior and is modeled using a unique energy-transfer process. The results obtained indicate that some Er-related luminescence centers are efficiently activated by direct excitation of electrons to some traps related to the luminescence centers.

Atom configuration study of δ-doped Er in InP by fluorescence EXAFS

Abstract We have investigated OMVPE-grown InP δ-doped with Er by EXAFS. The EXAFS measurement revealed that Er atoms which were δ-doped in InP by exposing to Er source for 15 min at 530°C (15 min Er-exposed sample) formed NaCl-structure ErP whose ErP bond length was 2.80 ± 0.03 A. The 10 min Er-exposed sample at 580°C showed a spectrum similar to cubic bixbyite structure Er 2 O 3 which was not observed in uniformly Er-doped InP samples. For the 40 min Er-exposed sample at 530°C, Er atoms formed both ErP and Er 2 O 3 .

Layer structure analysis of Er δ-doped InP by x-ray crystal truncation rod scattering

The layer structure and crystal structure of an Er δ-doped layer in InP are analyzed in a one monolayer (ML) level by an x-ray crystal truncation rod (CTR) scattering measurement using synchrotron radiation. The Er δ-doped InP sample is prepared by organometallic vapor phase epitaxy using trimethylindium, tertiarybutylphosphine, and tris(methyl-cyclopentadienyl)erbium as source materials. The analysis is made by comparing the measured CTR spectra and theoretically generated ones assuming four possible crystal structures for the Er δ-doped layers. We reveal that the Er atoms in InP form the rocksalt structure ErP. In the analysis of the crystal structure the x-ray interference plays a vital role. Er distribution in the δ-doped layer is clearly resolved in 1 ML level. It is shown that the Er atoms are well confined in 5 ML(15 A) thickness. The total amount of Er atoms is 0.171 ML, which is quite close to 0.2 ML obtained by Rutherford backscattering measurement on the same sample.

Local structure study of dilute Er in III-V semiconductors by fluorescence EXAFS.

For understanding the luminescence of Er atoms in III-V semiconductors, OMVPE-grown InP doped with Er has been investigated by fluorescence EXAFS (extended X-ray absorption fine structure) in order to study the local structure around Er atoms. The local structures around the Er atoms doped in InP, with doping as dilute as 3 x 10(12) Er atoms in a 1.5 mm x 1.0 mm spot, were successfully measured by fluorescence EXAFS. The EXAFS analysis revealed that the Er atoms doped in InP above 853 K (which showed low luminescence) formed the rock-salt-structure ErP, while the Er atoms doped in InP below 823 K (which showed high luminescence) substituted on the In site of InP. The dependence of the local structure on growth temperature was observed for the samples doped with 3 x 10(12) atoms and 1.2 x 10(13) atoms of Er.

OBSERVATION OF TRAP STATES IN ER-DOPED INP BY PHOTOREFLECTANCE

We have investigated room-temperature photoreflectance (PR) spectra in Er-doped InP grown by low-pressure organometallic vapor phase epitaxy. A new feature is clearly observed at 1.31 eV, accompanied with a feature due to the bandgap transition at 1.35 eV. The new feature is attributed to a transition involving an Er trap. The transition energy is independent of both doping processing techniques and concentrations of Er in the layers. The PR spectral width of the trap transition energy described by the broadening parameter, increases linearly with the logarithm of Er concentrations.

Local structures around Er atoms doped in InP revealed by fluorescence EXAFS

We have investigated OMVPE-grown InP doped with Er by fluorescence EXAFS (extended X-ray absorption fine structure) in order to study the local structures around Er atoms, so as to understand the luminescence property of Er atoms in semiconductors. The EXAFS analysis revealed that the Er atoms substituted into the In-site of InP, in the samples grown below 550°C, which exhibited high efficiency of luminescence, while the Er atoms constructed the NaCl-structure ErP, in the samples grown above 580°C, which exhibited low efficiency of luminescence.

Structural analysis of erbium δ-doped InP(001) crystal by means of RBS channeling☆

Abstract The lattice location of Er δ-doped in InP(001) crystal by organometallic vapor phase epitaxy (OMVPE) was carried out by means of Rutherford backscattering spectrometry (RBS) with the channeling technique. The Er yield curve around the 〈001〉 direction shows a small dip and those around the 〈011〉 and 〈111〉 directions show a small flux peak. The flux peak along the 〈111〉 is lower than that along the 〈011〉 direction. These data suggest that Er atoms occupy a site equivalent to the hexahedral one in the InP lattice.

Characterization of InP δ-doped with Er by FFT photoreflectance

Abstract InP δ-doped with erbium (Er) by organometallic vapour phase epitaxy (OMVPE) has been systematically investigated by room-temperature photoreflectance (PR) spectroscopy. The PR spectra are observed with many periods of Franz-Keldysh oscillation (FKO) above the band-gap energy due to an electric field existing in the epitaxial layer. Fast Fourier transform (FFT) is successfully applied to the PR spectra to calculate the electric field precisely from the FKO. The transformed spectra exhibit two peaks clearly. The main peak corresponds to the FKO, while the other peak to the split-off transition. The electric field deduced from FKO decreases with the increasing cap-layer thickness and the Er-exposure duration. Behaviours of the electric fields are discussed based on the existence of ErP.