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Threshold Current Density (threshold + current_density)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Effect of stack number on the threshold current density and emission wavelength in quantum dash/dot lasers

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2009
D. Zhou
Abstract InAs quantum dash and dot (QDH and QD) lasers grown by molecular beam epitaxy on InP substrate are studied. The grown lasers with active zone containing multiple stacked layers exhibit lasing wavelength at 1.55 ,m. On these devices, the experimental threshold current density reaches its minimum value for a double stacked QDH/QD structure. Other basic laser properties like gain and quantum efficiency are compared. QD lasers exhibit better threshold current densities but equivalent modal gain per layer than QDH. Finally, the analysis of the modal gain on QD laser structures shows a promising potential for improvement of the laser properties. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Switching thresholds in MTJ using SPICE model , Effects of spin and Ampere torques

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2008
M. Malathi
Abstract Spin torque due to spin polarized tunneling current can be used to switch the free layer in a magnetic tunnel junction (MTJ). This current also gives rise to an Ampere torque, which influences the switching threshold of the MTJ. We modified the Landau,Lifschitz,Gilbert equation (LLGE) to include an Ampere torque term and solved for the magnetization dynamics under the single domain approximation using a linear solver in SPICE. We also extend the model to a square array of MTJs to study the effect of nearest neighbour interactions in addition to effects like demagnetization and magnetostatic interactions with the pinned layer. The interlayer exchange field between the free and pinned layers of a MTJ and the spin torque are competing factors that decide the threshold current density for switching the MTJ. We used a two current model to study the effects of barrier height and barrier thickness on spin torque and exchange energy. We observe that both the spin torque and exchange energy decrease with an increase in barrier height (for ferromagnetic coupling) and barrier thickness. We find that the inclusion of Ampere torque causes a reduction in the switching current. Varying the thickness of MgO and Al2O3 barriers allows us to minimize the switching threshold voltage. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effect of stack number on the threshold current density and emission wavelength in quantum dash/dot lasers

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2009
D. Zhou
Abstract InAs quantum dash and dot (QDH and QD) lasers grown by molecular beam epitaxy on InP substrate are studied. The grown lasers with active zone containing multiple stacked layers exhibit lasing wavelength at 1.55 ,m. On these devices, the experimental threshold current density reaches its minimum value for a double stacked QDH/QD structure. Other basic laser properties like gain and quantum efficiency are compared. QD lasers exhibit better threshold current densities but equivalent modal gain per layer than QDH. Finally, the analysis of the modal gain on QD laser structures shows a promising potential for improvement of the laser properties. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Stimulated emission and leakage current in InxGa1,xN lasers

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005
Elis Mon
Abstract In this paper we calculate the temperature dependence of the transparency concentration n0 for InxGa1,xN/GaN single quantum well laser diodes. To establish the lasing mechanism existing in these lasers, this concentration is compared with that given by the Mott criterion limiting the existence of an excitonic gas or electron-hole plasma. For a typical structure with an In0.13Ga0.87N active layer n0 results higher than the critical excitonic concentration. This result indicates that the conventional electron-hole plasma instead of excitonic recombination is the dominant mechanism responsible for lasing in nitride lasers. The contribution of the diffusion leakage current density to the total threshold current density was also calculated, considering both electron and hole components. We obtain that the electron leakage current density is more than a half of the total threshold current density, confirming it is the main loss mechanism present in these lasers. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]