@article{78604ff905bf4c98bec3c3583a27ee35,
title = "Effects of rapid thermal annealing on device characteristics of InGaAs/ GaAs quantum dot infrared photodetectors",
abstract = "In this work, rapid thermal annealing was performed on InGaAsGaAs quantum dot infrared photodetectors (QDIPs) at different temperatures. The photoluminescence showed a blueshifted spectrum in comparison with the as-grown sample when the annealing temperature was higher than 700 °C, as a result of thermal interdiffusion of the quantum dots (QDs). Correspondingly, the spectral response from the annealed QDIP exhibited a redshift. At the higher annealing temperature of 800 °C, in addition to the largely redshifted photoresponse peak of 7.4 μm (compared with the 6.1 μm of the as-grown QDIP), a high energy peak at 5.6 μm (220 meV) was also observed, leading to a broad spectrum linewidth of 40%. This is due to the large interdiffusion effect which could greatly vary the composition of the QDs and thus increase the relative optical absorption intensity at higher energy. The other important detector characteristics such as dark current, peak responsivity, and detectivity were also measured. It was found that the overall device performance was not affected by low annealing temperature, however, for high annealing temperature, some degradation in device detectivity (but not responsivity) was observed. This is a consequence of increased dark current due to defect formation and increased ground state energy.",
keywords = "Ground state, Light absorption, Semiconducting indium gallium arsenide, Semiconductor quantum dots, Spectrum analysis, Thermal effects, Thermoanalysis",
author = "L. Fu and Tan, {H. H.} and I. McKerracher and J. Wong-Leung and C. Jagadish and N. Vukmirovi{\'c} and P. Harrison",
note = "Funding Information: The authors would like to thank M. Aggett, T. Halstead, and D. Gibson for their continuous technical assistance. The financial support from Australian Research Council is also acknowledged. Table I. Summary of device properties for all the QDIPs studied in this work. QDIPs Bias(V) Darkcurrentdensity ( A ∕ cm 2 ) Peakposition ( μ m ) Peakresponsivity (mA/W) Peakdetectivity(cm Hz 1 ∕ 2 ∕ W ) As-grown 1.3 4.98 × 10 − 6 6.1 6.9 1.58 × 10 9 RTA 650 ° C 1.1 1.1 × 10 − 5 6 9.6 1.89 × 10 9 RTA 700 ° C 1 5.33 × 10 − 6 6.5 5 1.27 × 10 9 RTA 800 ° C (long wavelength peak) 1.3 7.93 × 10 − 4 7.4 10.5 4 × 10 8 FIG. 1. (a) Bottom: XTEM image of the as-grown 15-layer QDIP structure; top: High resolution XTEM image of a single QD within the 15-layer QDIP structure. (b) Room temperature PL from the as-grown 15-layer QDIP structure. FIG. 2. The 77 K PL spectra for the QDIP samples annealed at different temperatures. Inset shows the PL energy shifts (right) and the linewidth (left) as a function of annealing temperature. FIG. 3. The spectral response from the as-grown QDIP at various external biases at 77 K . FIG. 4. The calculated spectrum of optical absorption cross sections for 65% In Ga As ∕ Ga As QDs. Inset shows the schematic of the conduction band diagram and relevant energy levels. FIG. 5. The spectral responses at 1.2 V from the QDIPs which were fabricated from samples annealed at different temperatures. Inset shows the device intersubband transition wavelength shift (right) as well as the energy shift (left) as a function of annealing temperature for annealed QDIPs compared with the as-grown QDIP. FIG. 6. (a) The spectral responses from the 800 ° C annealed QDIP at various positive biases. (b) The calculated spectrum of optical absorption cross sections for 50% In Ga As ∕ Ga As QDs. FIG. 7. The I - V characteristics for the as-grown QDIP measured at different temperatures. The 300 K background photocurrent measured at 77 K is also shown. FIG. 8. The dark current density versus inverse temperature ( 1000 ∕ T ) at various biases for the as-grown QDIP. The linear section at the high temperature region ( > 125 K ) of the curves is used to estimate the dark current activation energy. Inset plots the calculated dark current activation energy as a function of bias. FIG. 9. (a) The 77 K I - V characteristics for the annealed QDIPs compared with the as-grown QDIP. (b) The dark current density versus inverse temperature ( 1000 ∕ T ) for the annealed QDIPs compared with the as-grown QDIP at 0.3 V . FIG. 10. (a) The bias dependence of peak responsivity for the annealed QDIPs compared with the as-grown QDIP. (b) The bias dependence of peak detectivity for the annealed QDIPs compared with the as-grown QDIP. ",
year = "2006",
month = jun,
day = "1",
doi = "10.1063/1.2202704",
language = "English",
volume = "99",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "11",
}