Molecular beam epitaxy and properties of GaAsBi/GaAs quantum wells grown by molecular beam epitaxy: effect of thermal annealing

Abstract

We have grown GaAsBi quantum wells by molecular beam epitaxy. We have studied the properties of a 7% Bi GaAsBi quantum well and their variation with thermal annealing. High-resolution X-ray diffraction, secondary ion mass spectrometry, and transmission electron microscopy have been employed to get some insight into its structural properties. Stationary and time-resolved photoluminescence shows that the quantum well emission, peaking at 1.23 μm at room temperature, can be improved by a rapid annealing at 650°C, while the use of a higher annealing temperature leads to emission degradation and blue-shifting due to the activation of non-radiative centers and bismuth diffusion from the quantum well.

Optical properties of GaBiAs single quantum well structures grown by MBE

“…Based on those results, we assumed a thin layer of GaBiAs with ∼1.2% Bi concentration at the interface and made a rough calculation which corresponds to 1.31 eV-i.e. the capping side of the QW Bi concentration is not abrupt [8]. The line-width of the PR spectra tends to broaden when Bi concentration is increased, due to an increased number of localized states, as expected in highly mismatched alloys (HMAs).…”

“…As indicated by the SIMS results [8], we expect that the conduction band edge fluctuation is relatively low within the QW, compared to the bulk structure; in addition, the Bicontaining layers are very thin. However, above 2% Bi concentration, Bi distribution in the host material is random and forms clusters that cause a localized state just above the VBE; it is also known that Bi clusters in GaAs host material have different bonding configurations and therefore different binding energies.…”

“…The GaBi 0.07 As 0.93 PL spectrum has the same asymmetric line shape, but the shoulder is not present, as seen in the inset of figure 3. The inset also shows that PL intensity decreases with increasing Bi concentration due to the increasing number of Bi-related non-radiative centers and small localized states caused by increased compressive strain [8]. The optical transition energies obtained from PL and PR are different.…”

“…The peak corresponding to 1.31 eV is not clear. But an independent investigation on the same samples by Makhloufi et al determined the Bi profile through the GaBi 0.07 As 0.93 structure by secondary ion mass spectrometry (SIMS) [8]. Their results showed that Bi profile in the growth direction had a step-like profile, coinciding with the QW region, but they also observed a slight Bi shoulder in the interface, between the QW layer and the top barrier layer.…”

Optical properties of GaBiAs single quantum well structures grown by MBE

“…Based on those results, we assumed a thin layer of GaBiAs with ∼1.2% Bi concentration at the interface and made a rough calculation which corresponds to 1.31 eV-i.e. the capping side of the QW Bi concentration is not abrupt [8]. The line-width of the PR spectra tends to broaden when Bi concentration is increased, due to an increased number of localized states, as expected in highly mismatched alloys (HMAs).…”

“…As indicated by the SIMS results [8], we expect that the conduction band edge fluctuation is relatively low within the QW, compared to the bulk structure; in addition, the Bicontaining layers are very thin. However, above 2% Bi concentration, Bi distribution in the host material is random and forms clusters that cause a localized state just above the VBE; it is also known that Bi clusters in GaAs host material have different bonding configurations and therefore different binding energies.…”

“…The GaBi 0.07 As 0.93 PL spectrum has the same asymmetric line shape, but the shoulder is not present, as seen in the inset of figure 3. The inset also shows that PL intensity decreases with increasing Bi concentration due to the increasing number of Bi-related non-radiative centers and small localized states caused by increased compressive strain [8]. The optical transition energies obtained from PL and PR are different.…”

“…The peak corresponding to 1.31 eV is not clear. But an independent investigation on the same samples by Makhloufi et al determined the Bi profile through the GaBi 0.07 As 0.93 structure by secondary ion mass spectrometry (SIMS) [8]. Their results showed that Bi profile in the growth direction had a step-like profile, coinciding with the QW region, but they also observed a slight Bi shoulder in the interface, between the QW layer and the top barrier layer.…”

Influence of laser irradiation on optical properties of GaAsBi/GaAs quantum wells

“…Temperatures of 600-700°C used in rapid thermal annealing were shown to be sufficient for the restructuration of GaAsBi structures [9,12]. Since the photon energy of He-Cd laser radiation Fig.…”

Optical properties of GaBiAs single quantum well structures grown by MBE

“…Based on those results, we assumed a thin layer of GaBiAs with ∼1.2% Bi concentration at the interface and made a rough calculation which corresponds to 1.31 eV-i.e. the capping side of the QW Bi concentration is not abrupt [8]. The line-width of the PR spectra tends to broaden when Bi concentration is increased, due to an increased number of localized states, as expected in highly mismatched alloys (HMAs).…”

“…As indicated by the SIMS results [8], we expect that the conduction band edge fluctuation is relatively low within the QW, compared to the bulk structure; in addition, the Bicontaining layers are very thin. However, above 2% Bi concentration, Bi distribution in the host material is random and forms clusters that cause a localized state just above the VBE; it is also known that Bi clusters in GaAs host material have different bonding configurations and therefore different binding energies.…”

“…The GaBi 0.07 As 0.93 PL spectrum has the same asymmetric line shape, but the shoulder is not present, as seen in the inset of figure 3. The inset also shows that PL intensity decreases with increasing Bi concentration due to the increasing number of Bi-related non-radiative centers and small localized states caused by increased compressive strain [8]. The optical transition energies obtained from PL and PR are different.…”

“…The peak corresponding to 1.31 eV is not clear. But an independent investigation on the same samples by Makhloufi et al determined the Bi profile through the GaBi 0.07 As 0.93 structure by secondary ion mass spectrometry (SIMS) [8]. Their results showed that Bi profile in the growth direction had a step-like profile, coinciding with the QW region, but they also observed a slight Bi shoulder in the interface, between the QW layer and the top barrier layer.…”

Influence of laser irradiation on optical properties of GaAsBi/GaAs quantum wells

“…Temperatures of 600-700°C used in rapid thermal annealing were shown to be sufficient for the restructuration of GaAsBi structures [9,12]. Since the photon energy of He-Cd laser radiation Fig.…”

Optical properties of GaBiAs single quantum well structures grown by MBE

“…Based on those results, we assumed a thin layer of GaBiAs with ∼1.2% Bi concentration at the interface and made a rough calculation which corresponds to 1.31 eV-i.e. the capping side of the QW Bi concentration is not abrupt [8]. The line-width of the PR spectra tends to broaden when Bi concentration is increased, due to an increased number of localized states, as expected in highly mismatched alloys (HMAs).…”

“…As indicated by the SIMS results [8], we expect that the conduction band edge fluctuation is relatively low within the QW, compared to the bulk structure; in addition, the Bicontaining layers are very thin. However, above 2% Bi concentration, Bi distribution in the host material is random and forms clusters that cause a localized state just above the VBE; it is also known that Bi clusters in GaAs host material have different bonding configurations and therefore different binding energies.…”

“…The GaBi 0.07 As 0.93 PL spectrum has the same asymmetric line shape, but the shoulder is not present, as seen in the inset of figure 3. The inset also shows that PL intensity decreases with increasing Bi concentration due to the increasing number of Bi-related non-radiative centers and small localized states caused by increased compressive strain [8]. The optical transition energies obtained from PL and PR are different.…”

“…The peak corresponding to 1.31 eV is not clear. But an independent investigation on the same samples by Makhloufi et al determined the Bi profile through the GaBi 0.07 As 0.93 structure by secondary ion mass spectrometry (SIMS) [8]. Their results showed that Bi profile in the growth direction had a step-like profile, coinciding with the QW region, but they also observed a slight Bi shoulder in the interface, between the QW layer and the top barrier layer.…”

Influence of laser irradiation on optical properties of GaAsBi/GaAs quantum wells

“…Temperatures of 600-700°C used in rapid thermal annealing were shown to be sufficient for the restructuration of GaAsBi structures [9,12]. Since the photon energy of He-Cd laser radiation Fig.…”