Surface photovoltage spectroscopy characterization of a GaAs/GaAlAs vertical-cavity-surface-emitting-laser structure: Angle dependence

Liang, J. S.; Huang, Ying; Tien, C. W.; Chang, Yu‐Ming; Chen, C. W.; Li, N. Y.; Li, Peiwen; Pollak, Fred H.

doi:10.1063/1.1418027

Cited by 10 publications

(4 citation statements)

References 13 publications

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“…The resonance wavelength of the vertical cavity structure was determined from SPVS, where the photo-voltage induced by light incident on the surface of the wafer is measured [32][33][34]. A sharp peak in the photo-voltage is seen at the cavity resonance wavelength due to a higher photon density, within the vertical cavity, increasing the number of electron-hole pairs generated at the active region.…”

Section: Methodsmentioning

confidence: 99%

Gain measurements on VCSEL material using segmented contact technique

Hentschel

Allford²,

Gillgrass³

et al. 2023

J. Phys. D: Appl. Phys.

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We report direct measurements of the optical gain on vertical-cavity surface-emitting laser (VCSEL) material using a stripe-length method featuring segmented contacts. We utilise the similarity of the in-plane transverse electric (TE) polarised matrix element and that of the VCSEL lasing mode and a simple method to reduce round trip effects. The confinement factor is determined from cold-cavity simulations of the in-plane TE polarised slab waveguide mode and used to convert the measured in-plane modal gain into the vertical-cavity modal gain, as required for the VCSEL structure. This gives a threshold material gain of 1440 ± 140 cm−1 at 30 °C for this structure. A comparison with the threshold material gain values determined from the lasing condition, where internal optical losses due to doping induced absorption is included using parameters taken from the literature, indicates the presence of an additional source of optical loss in the experiment which increases the threshold material gain by ∼450 cm−1. A best fit is obtained by increasing the optical loss in the n-DBR (distributed Bragg reflectors) layers to 40 cm−1, which is consistent with previous work on additional scattering losses due to interface roughening in the n-DBR layers. To further demonstrate the utility of this method for rapid optimisation, the gain-peak wavelength is measured directly, and its temperature dependence is compared to the lasing wavelength.

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Section: Methodsmentioning

confidence: 99%

Gain measurements on VCSEL material using segmented contact technique

Hentschel

Allford²,

Gillgrass³

et al. 2023

J. Phys. D: Appl. Phys.

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“…More time-consuming measurements, such as wavelength variation with current and temperature, were performed on a reduced number of devices based on L-I-V-λ screening. Additionally, surface photovoltage spectroscopy (SPVS) [31][32][33] was used to Fabrication followed common processing techniques which, for the standard VCSEL structures was as follows: definition of the mesa by inductively coupled plasma (ICP) etch to just below the active layers, a depth of ~3 µm. Wet thermal oxidation of the samples at 400 • C to form the oxide apertures with an oxidation depth of 5.5 ± 0.5 µm.…”

Section: Methodsmentioning

confidence: 99%

“…More time-consuming measurements, such as wavelength variation with current and temperature, were performed on a reduced number of devices based on L-I-V-λ screening. Additionally, surface photovoltage spectroscopy (SPVS) [31][32][33] was used to measure the cavity mode wavelength of the epi-material. SPVS involves shining wavelength-varied monochromatic light normal to the surface of the sample and measuring the voltage induced as photogenerated electron-hole pairs are separated by the built-in field.…”

Section: Methodsmentioning

confidence: 99%

Quick Fabrication VCSELs for Characterisation of Epitaxial Material

et al. 2021

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A systematic analysis of the performance of VCSELs, fabricated with a decreasing number of structural elements, is used to assess the complexity of fabrication (and therefore time) required to obtain sufficient information on epitaxial wafer suitability. Initially, sub-mA threshold current VCSEL devices are produced on AlGaAs-based material, designed for 940 nm emission, using processing methods widely employed in industry. From there, stripped-back Quick Fabrication (QF) devices, based on a bridge-mesa design, are fabricated and this negates the need for benzocyclcobutane (BCB) planarisation. Devices are produced with three variations on the QF design, to characterise the impact on laser performance from removing time-consuming process steps, including wet thermal oxidation and mechanical lapping used to reduce substrate thickness. An increase in threshold current of 1.5 mA for oxidised QF devices, relative to the standard VCSELs, and a further increase of 1.9 mA for unoxidised QF devices are observed, which is a result of leakage current. The tuning of the emission wavelength with current increases by ~0.1 nm/mA for a VCSEL with a 16 μm diameter mesa when the substrate is unlapped, which is ascribed to the increased thermal resistance. Generally, relative to the standard VCSELs, the QF methods employed do not significantly impact the threshold lasing wavelength and the differences in mean wavelengths of the device types that are observed are attributed to variation in cavity resonance with spatial position across the wafer, as determined by photovoltage spectroscopy measurements.

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“…SPV signals are essentially approximately proportional to the absorption spectrum of the sample and, in the case of QWs, can yield simple peaks near the excitonic transitions [6]. Such signals can be analysed by several methods [4,[7][8][9]. Here we adopted the procedure recommended by Ref.…”

Section: Analysis Techniquesmentioning

confidence: 99%

Room temperature characterisation of InGaAlAs quantum well laser structures using electro‐modulated reflectance and surface photovoltage spectroscopy

Fox

Sharma

Sweeney

et al. 2009

Physica Status Solidi (a)

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In this study, two tri‐metal quaternary InGaAlAs quantum well (QW) laser structures grown on InP are compared to a conventional InGaAsP QW structure, also grown on InP, all designed to lase at 1.55 μm. Several spectroscopic methods are used to study the samples including surface photo‐voltage (SPV) and electro‐modulated reflectance (ER). In the tri‐metal samples the ground‐ and two excited‐state QW transitions are detectable in both types of spectroscopy. The SPV and ER give results in agreement to within a few meV of each other. By comparing the position of the measured QW transitions with those predicted theoretically, the conduction band offsets of the tri‐metal samples can be determined and compared to that in the InGaAsP sample. It is found that the tri‐metal samples have a much larger conduction band offset of ∼66% compared to the ∼40% in the InGaAsP sample. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Surface photovoltage spectroscopy characterization of a GaAs/GaAlAs vertical-cavity-surface-emitting-laser structure: Angle dependence

Cited by 10 publications

References 13 publications

Gain measurements on VCSEL material using segmented contact technique

Gain measurements on VCSEL material using segmented contact technique

Quick Fabrication VCSELs for Characterisation of Epitaxial Material

Room temperature characterisation of InGaAlAs quantum well laser structures using electro‐modulated reflectance and surface photovoltage spectroscopy

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