Titre :

Low-temperature-grown gallium arsenide photoconductors with subpicosecond carrier lifetime and photoresponse reaching 25 mA/W under 1550 nm CW excitation

Auteur(s) :

Tannoury, Charbel [Auteur]
Billet, Maximilien [Auteur]
Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 [PhLAM]
Coinon, Christophe [Auteur]
Centrale de Micro Nano Fabrication - IEMN [CMNF - IEMN]
Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 [IEMN]
Lampin, Jean-Francois [Auteur]
Peytavit, Emilien [Auteur]
Photonique THz - IEMN [PHOTONIQUE THZ - IEMN]
Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 [IEMN]

Titre de la revue :

Electronics Letters

Pagination :

897-899

Éditeur :

IET

Date de publication :

2020-08-20

ISSN :

0013-5194

Mot(s)-clé(s) en anglais :

annealing
gallium arsenide
photoconducting materials
carrier lifetime
III‐V semiconductors
low‐temperature‐grown gallium arsenide photoconductors
subpicosecond carrier lifetime
photoresponse
CW excitation
photoresponses
continuous‐wave
1550‐nm‐wavelength illumination
optical Fabry‐Perot cavity
post‐growth annealing temperature
external quantum efficiency
temperature 450.0 degC
wavelength 1550.0 nm
GaAs

Discipline(s) HAL :

Sciences de l'ingénieur [physics]

Résumé en anglais : [en]

The authors show in this Letter that photoconductors based on GaAs grown at low temperatures can exhibit photoresponses as high as 25 mA/W under continuous-wave 1550-nm-wavelength illumination. It is achieved by using an ...
Lire la suite >The authors show in this Letter that photoconductors based on GaAs grown at low temperatures can exhibit photoresponses as high as 25 mA/W under continuous-wave 1550-nm-wavelength illumination. It is achieved by using an optical Fabry-Pérot cavity in order to improve the external quantum efficiency and by decreasing the post-growth annealing temperature down-to 450°C. Introduction: Low-temperature-grown GaAs (LT-GaAs) photo-conductors have served as THz sources or detectors in time-domain THz spectroscopy systems based on Ti: Sa mode-locked lasers operating around 800 nm [1]. They have also been used as photoconductive switches to sample millimetre wave signals [2, 3], as optoelectronic homodyne mixers in CW THz spectroscopy systems [4] and also as optoelectronic heterodyne mixers in THz detectors [5, 6]. We have recently shown that LT-GaAs ultrafast photoconductors can operate at λ = 1550 nm, despite a photon energy E ph ≈ 0.75 eV, i.e. lower than the energy gap of GaAs (E g = 1.42 eV), by placing the LT-GaAs layer inside an optical resonant cavity [7]. This photoconductor has been then successfully used to sub-sample continuous waves at frequencies up to 300 GHz, demonstrating a sub-picosecond response time of photocurrents generated by 1550 nm illumination [8]. However, the much higher dark resistivity of LT-GaAs material (>10 3 kΩ cm) in comparison with LT-InGaAs/InAlAs multilayers material [9] or Fe-doped InGaAs layers [10] (<2 kΩ cm) employed in 1550-nm ultrafast photo-conductors is far from compensating the low photoresponse despite the use of an optical cavity (≈ 1 mA/W under CW illumination [7]). These first results have been obtained by using an LT-GaAs layer grown at a temperature of 250 ± 5°C and annealed at 580°C during 60 s. The post-grown annealing is performed in order to decrease the number of point defects (As Ga , As i , V Ga) related to the incorporation of excess arsenic in the layer by forming As clusters. It has been demonstrated several times that it leads mainly to a higher dark resistivity, a lower sub-bandgap absorption [11] and a slight increase of the carrier-lifetime. In this Letter, we show that a photoresponse under CW illumination reaching 25 mA/W can be achieved by decreasing the post-growth annealing temperature down to 450°C. This is 25% of the value obtained using the same type of resonant-cavity-enhanced LT-GaAs photoconductor under 800-nm-wavelength illumination. Under this condition, a dark resistivity of 200 kΩ cm has been measured, which is still two orders of magnitude greater than that of best InGaAs-based ultrafast photoconductive materials [10]. In addition, a clear dependence of the photoresponse and dark resistivity on the post-annealing temperature is shown in the temperature range 450-580°C.Lire moins >

Langue :

Anglais

Vulgarisation :

Non

Collections :

• Institut d'Électronique, de Microélectronique et de Nanotechnologie (IEMN) - UMR 8520

Source :

Harvested from HAL