Gain In In0 Research Articles

Lateral carrier diffusion and current gain in terahertz InGaAs/InP double-heterojunction bipolar transistors

The DC current gain in In0.53Ga0.47As/InP double-heterojunction bipolar transistors is computed based on a drift-diffusion model, and is compared with experimental data. Even in the absence of other scaling effects, lateral diffusion of electrons to the base Ohmic contacts causes a rapid reduction in DC current gain as the emitter junction width and emitter-base contact spacing are reduced. The simulation and experimental data are compared in order to examine the effect of carrier lateral diffusion on current gain. The impact on current gain due to device scaling and approaches to increase current gain are discussed.

Differential Gain in InGaAsN/GaAs Double Quantum Well Structures by Numerical Simulations

We performed numerical studies of differential gain in a coupled quantum well structures built from InGaAsN. Differential gain in In0.38Ga0.62As1_yNy/GaAs quantum well structures was determined and analyzed. A 10‐band k_p Hamiltonian matrix was used in the calculations and solved self‐consistently with Poisson′s equation. The effect of Nitrogen composition and barrier thickness on differential gain has been determined. The influence of Nitrogen composition on differential gain is significant whereas barrier effects are modest.

Analysis of gain saturation in In0.02Ga0.98N/In0.16Ga0.84N multiple quantum wells

A way of analyzing the data in a variable stripe length method gain experiment is presented. We confirm that the stripe length dependence of the gain in In0.02Ga0.98N/In0.16Ga0.84N multiple quantum wells is caused by the change of the chemical potential along the excited stripe due to the interaction of the carrier and photon densities, and the gain threshold density is estimated. A trial function assuming a Lorentzian line shape for the stripe length dependence of the gain is compared with the edge emission intensity as a function of the stripe length. This is found to fit very well with our data, even beyond the saturation region.

Calculated absorption, emission, and gain in In0.72Ga0.28As0.6P0.4

The absorption, emission, and gain spectra of In0.72Ga0.28As0.6P0.4 (λg =1.3 μm), which lattice matches InP, is calculated using a Gaussian fit to Halperin-Lax band tails and Stern’s matrix element. The calculation is done both for p- and n-type material at various impurity concentrations. The spectral width of emission increases both with increasing doping and impurity concentration. All results are for 297 K. The gain-versus-excitation rate is given by the equation g (cm−1)=0.057 (Jnom −2400), where Jnom is the nominal current density in the active layer expressed in A/cm2 μm. Also, the photon energy at maximum gain increases with increasing excitation rate.