Examinando por Autor "Esquivias, Ignacio"

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Carrier Capture and Escape Processes in In Ga As-GaAs Quantum-Well Lasers
(IEEE, 1999) Romero, Beatriz; Esquivias, Ignacio; Weisser, Stephan; Larkings, Eric; Rosen, Joseph
We have extracted the ratio between the carrier capture and escape times, eta, for In0.25Gao0.75As-GaAs lasers containing one, two, or three quantum wells, from high-frequency subthreshold impedance measurements at different temperatures. Our results show that the carrier capture process dominates over the diffusion along the confinement region in the overall transport/capture process. The obtained value for eta is comparable to unity, and this fact has to be taken into account to obtain real material parameters, such as the carrier lifetime and the radiative recombination coefficient.
Carrier capture and escape times in In0.35Ga0.65As-GaAs multiquantum-well lasers determined from high-frequency electrical impedance measurements
(IEEE, 1996-10) Esquivias, Ignacio; Weisser, Stephan; Romero, Beatriz; Ralston, John
We present experimental results on the high-frequency electrical impedance of In0.35Ga0.65As-GaAs multiquantum-well lasers with varied p-doping levels in the active region, The analysis of the data, using a simple three rate equation model, provides information about the dynamical time constants (the carrier lifetime, the effective carrier capture and escape times) under the laser operation conditions, The addition of p-doping increases the carrier escape time at threshold from 0.7 ns, extracted for the undoped devices, up to a value higher than 2 ns for the p-doped lasers, The effective capture time is estimated to be between 2 and 5 ps.
Carrier Dynamics and microwave characteristics of GaAs-Based Quantum-Well Lasers
(IEEE Journal of quantum electronics, 1999-04) Esquivias, Ignacio; Weisser, Stephan; Romero, Beatriz; Ralston, John; Rosenzweig, Joseph
We investigate the effects of carrier capture and re-emission on the electrical impedance, equivalent circuit, and modulation response of quantum-well (QW) laser diodes. The electrical impedance is shown to be a sensitive function of the time constants associated with carrier capture/transport and carrier re-emission. We compare the theoretical results with measured values of the electrical impedance of high-speed InGaAs-GaAs multiple-quantum-well lasers fabricated using different epilayer structures with a common lateral structure. The experimental results agree well with the theoretical model, allowing us to extract the effective carrier escape time and the effective carrier lifetime in the QW's, and to estimate the effective carrier capture/transport time
Damping limited modulation bandwidths up to 40 GHz in undoped short-cavity InGaAs-GaAs multiple quantum well lasers
(IEEE, 1996) Weisser, stephan; Larkins, Eric; Czotscher, Konrad; Benz, W; Daleiden, J; Esquivias, Ignacio; Fleissner, J; Ralston, John; Romero, Beatriz; Sah, RE; Schönferlder, Alexander; Rosenzweig, Joseph
We demonstrate record direct modulation bandwidths from MBE-grown In0.5Ga0.65As-GaAs multiple-quantum-well lasers with undoped active regions and with the upper and lower cladding layers grown at different growth temperatures, Short-cavity ridge waveguide lasers achieve CW direct modulation bandwidths up to 40 GHz for 6 x 130 mu m(2) devices at a bias current of 155 mA, which is the damping limit for this structure, We further demonstrate large-signal digital modulation up to 20 Gb/s (limited by the measurement setup) and linewidth enhancement factors of 1.4 at the lasing wavelength at threshold of similar to 1.1 mu m for these devices.
Impedance characteristics of quantum well lasers
(IEEE, 1994) Weisser, Stephan; Esquivias, Ignacio; Tasker, PJ; Ralston, John; Romero, Beatriz; Rosenzweig, Joseph
We derive theoretical expressions for the impedance of quantum-well lasers below and above threshold based on a simple rate equation model, These electrical laser characteristics are shown to be dominated by purely electrical parameters related to carrier capture/transport and carrier re-emission, The results of on-wafer measurements of the impedance of high-speed In0.35Ga0.65As/GaAs multipie-quantum-well lasers are shown to be in good agreement with this simple model, allowing us to extract the effective carrier escape time and the effective carrier lifetime, and to estimate the effective carrier capture/transport time,
Incorporation of carrier capture and escape processes into a self-consistent cw model for Quantum Well lasers
(Elsevier, 2003) Borruel, Luis; Arias, Julia; Romero, Beatriz; Esquivias, Ignacio
We describe a one-dimensional model for the simulation of the cw properties of Quantum Well laser diodes, which incorporates self-consistently the carrier capture/escape processes into the complete semiconductor equations. The approach is applied to simulate some laser structures properties that can only be described considering carrier capture effects. We point out the importance of these processes in the performance of high power laser diodes operating under cw conditions
Simple model for calculating the ratio of the carrier capture and escape times in quantum-well lasers
(American institute of Physics, 2000-03-20) Romero, Beatriz; Arias, Julia; Esquivias, Ignacio; Cada, Michael
We have developed a simple model for the carrier capture and escape processes in quantum-well (QW) lasers, which yields an analytical expression for the ratio of the carrier capture and escape times. It predicts a decrease in the escape time with injected carrier density due to the state filling effect. It also shows an exponential dependence of the escape time on the effective barrier height and on the inverse of the temperature. A comparison between experimental and calculated values for InGaAs/GaAs QW lasers is presented showing a good agreement