Search results

Sort By:

Limit search:

Carrier Dynamics in Quantum Cascade Lasers

100%

Harrison P., Indjin D., Jovanović V., Mirčetić A., Ikonić Z., Kelsall R., McTavish J., Savić I., Vukmirović N., Milanović V.

Acta Physica Polonica A

2005

vol. 107

issue 1

75-81

A fully quantum-mechanical model for carrier scattering transport in semiconductor intersubband devices was applied to modelling of carrier dynamics in quantum cascade lasers. The standard model uses the envelope function and effective mass approximations to solve electron band structure under an applied bias. The k·p model has been employed in p-type systems where the more complex band structure requires it. The resulting wave functions are then used to evaluate all relevant carrier-phonon, carrier-carrier and alloy scattering rates from each quantised state to all others within the same and the neighbouring period. This piece of information is then used to construct a rate equation for the equilibrium carrier density in each subband and this set of coupled rate equations are solved self-consistently to obtain the carrier density in each eigenstate. The latter is a fundamental description of the device and can be used to calculate the current density and gain as a function of the applied bias and temperature, which in turn yields the threshold current and expected temperature dependence of the device characteristics. A recent extension which includes a further iteration of an energy balance equation also yields the electron (or hole) temperature over the subbands. This paper will review the method and describe its application to mid-infrared and terahertz, GaAs, GaN, and SiGe cascade laser designs.

Normal Incidence Mid-Infrared Photocurrent in AlGaN/GaN Quantum Well Infrared Photodetectors

81%

Sherliker B., Halsall M., Harrison P., Jovanović V., Indjin D., Ikonić Z., Parbrook P., Whitehead M., Wang T., Buckle P., Phillips J., Carder D.

Acta Physica Polonica A

2005

vol. 107

issue 1

174-178

We report the growth and characterization of AlGaN/GaN multiple quantum well structures designed to have intersubband transitions in the mid-infrared region of the spectrum. The samples were nominally undoped but were found to contain a high electron population in the wells induced by the local polarization fields. The sample was characterized by the use of the Raman spectroscopy and photocurrent spectroscopy. The Raman spectroscopy shows electronic Raman scattering from intersubband transitions in the AlGaN/GaN quantum wells. The e_1-e_2 and e_1-e_3 transitions of the confined 2d electron population in the wells can clearly be observed. A sample designed to absorb at 4μm was fabricated into mesa structures and the vertical photocurrent measured under normal incidence illumination from the free-electron laser FELIX. A wavelength and bias dependent photocurrent was observed in the mid-IR region of spectrum. The peak responsivity was of the order of 50μA/W at 4 K, the photocurrent still being measurable at room temperature.

Refine search results

2 Acta Physica Polonica A

2 2005

2 Harrison P.

2 Ikonić Z.

2 Indjin D.

2 Jovanović V.

1 Buckle P.

1 Carder D.

1 Halsall M.

1 Kelsall R.

1 McTavish J.

1 Milanović V.

1 Mirčetić A.

1 Parbrook P.

1 Phillips J.

1 Savić I.

1 Sherliker B.

1 Vukmirović N.

1 Wang T.

1 Whitehead M.

Search results

Carrier Dynamics in Quantum Cascade Lasers

Normal Incidence Mid-Infrared Photocurrent in AlGaN/GaN Quantum Well Infrared Photodetectors