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Material properties and performance of ErAs:In(Al)GaAs photoconductors for 1550 nm laser operation

Nandi, Uttam ; Mohammadi, Mahdad ; Lu, Hong ; Norman, Justin ; Gossard, Arthur C. ; Alff, Lambert ; Preu, Sascha (2022):
Material properties and performance of ErAs:In(Al)GaAs photoconductors for 1550 nm laser operation. (Publisher's Version)
In: Journal of Vacuum Science & Technology A, 39 (2), AIP, ISSN 0734-2101, e-ISSN 1520-8559,
DOI: 10.26083/tuprints-00020601,

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Item Type: Article
Origin: Secondary publication service
Status: Publisher's Version
Title: Material properties and performance of ErAs:In(Al)GaAs photoconductors for 1550 nm laser operation
Language: English

ErAs:In(Al)GaAs photoconductors have proven to be outstanding devices for photonic terahertz (0.1–10 THz) generation and detection with previously reported sub-0.5 ps carrier lifetimes. We present the so far most detailed material characterization of these superlattices composed of ErAs, InGaAs, and InAlAs layers grown by molecular beam epitaxy. The variation of the material properties as a function of the ErAs concentration and the superlattice structure is discussed with focus on source materials. Infrared spectroscopy shows an absorption coefficient in the range of 4700–6600 cm⁻¹ at 1550 nm, with shallow absorption edges toward longer wavelengths caused by absorption of ErAs precipitates. IV characterization and Hall measurements show that samples with only 0.8 monolayers of electrically compensated ErAs precipitates (p-delta-doped at 5 x 10¹³ cm⁻²) and aluminum-containing spacer layers enable high dark resistance (~10–20 MΩ) and high breakdown field strengths beyond 100 kV/cm, corresponding to > 500 V for a 50 μm gap. With higher ErAs concentration of 1.6 ML (2.4 ML), the resistance decreases by a factor of ~40 (120) for an otherwise identical superlattice structure. We propose a theoretical model for calculation of the excess current generated due to heating and for the estimation of the photocurrent from the total illuminated current. The paper concludes with terahertz time-domain spectroscopy measurements demonstrating the strengths of the material system and validating the proposed model.

Journal or Publication Title: Journal of Vacuum Science & Technology A
Journal volume: 39
Issue Number: 2
Publisher: AIP
Collation: 9 Seiten
Classification DDC: 500 Naturwissenschaften und Mathematik > 530 Physik
600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
18 Department of Electrical Engineering and Information Technology > Institute for Microwave Engineering and Photonics (IMP)
Date Deposited: 16 Feb 2022 13:43
Last Modified: 16 Feb 2022 13:44
DOI: 10.26083/tuprints-00020601
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-206014
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/20601
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