Anomalous photoluminescence in InP1−xBix

Abstract

Low temperature photoluminescence (PL) from InP1−xBix thin films with Bi concentrations in the 0–2.49% range reveals anomalous spectral features with strong and very broad (linewidth of 700 nm) PL signals compared to other bismide alloys. Multiple transitions are observed and their energy levels are found much smaller than the band-gap measured from absorption measurements. These transitions are related to deep levels confirmed by deep level transient spectroscopy, which effectively trap free holes and enhance radiative recombination. The broad luminescence feature is beneficial for making super-luminescence diodes, which can theoretically enhance spatial resolution beyond 1 μm in optical coherent tomography (OCT).

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…To act as a surfactant, there have to be enough Bi atoms impinged onto the matrix material [202]. If the Bi content is too high or the growth temperature is too low, Bi tends to segregate and even form droplets on the surface, deteriorating the material morphology.…”

Negative thermal quenching of below-bandgap photoluminescence in InPBi

“…16,18 The native P In donor level was indicated to be about 0.2-0.3 eV below the conduction band, 17,31 and the acceptor level due to Bi pairs/clusters was found at about 0.11 eV above the valence band in InP 0.975 Bi 0.025 . 17 In addition, theoretical simulations suggested that the Bi In anti-site exists in InPBi and the energetic level is located at about 0.39 eV below the conduction band of InPBi at RT.…”

“…17 In addition, theoretical simulations suggested that the Bi In anti-site exists in InPBi and the energetic level is located at about 0.39 eV below the conduction band of InPBi at RT. 33 It therefore seems to be a hint that the A-and B-features may be attributed to the Bi Into-Bi pairs/clusters and P In -to-Bi pairs/clusters transitions, respectively; and C-and D-features the Bi In -and P In -levels to the Bi pairs/clusters-irrelevant shallow-acceptor levels transitions.…”

“…12 For InP 1-x Bi x , which is compatible with InP-based devices and the bandgap reduction is as large as 60-80 meV/%Bi, [15][16][17][18][19] however, the bandedge PL emission is missing and an extraordinarily broad below-bandgap PL emission shows up in a range of 0.9-2.5 lm.…”

“…[12][13][14] For example, it was clarified for GaAsBi that the thermal quenching of bandedge PL is due to two-energy components of cluster localization and alloy disorder. 12 For InP 1-x Bi x , which is compatible with InP-based devices and the bandgap reduction is as large as 60-80 meV/%Bi, [15][16][17][18][19] however, the bandedge PL emission is missing and an extraordinarily broad below-bandgap PL emission shows up in a range of 0.9-2.5 lm. [15][16][17] While such a broad-band PL emission may open up a new application window for, e.g., super-broad infrared source covering the whole telecommunication spectral range, the thermal quenching of the broadband PL is yet to be clarified.…”