A model of carrier leakage lifetime is presented taking into account the density of states for quantum-wells and band nonparabolicity. Rate equations are also proposed including leakage of both types of carriers and carrier loss in both sides of optical confinement layers. The carrier loss coefficients extracted by adopting this model on the measured modulation bandwidth of 1.5 µm-wavelength multiquantum-well lasers coincided with reported values within their distributions. Measured temperature sensitivity of threshold current and that of K factor were also well explained with the improved model using those extracted carrier loss coefficients. The dominant causes of low characteristic temperature T 0 of present compressive-strained multiquantum-well lasers were quantitatively considered and found to be attributed to 1) Auger carrier loss and 2) thermionic carrier leakage and diffusion delay effect. T 0 over 150 K is expected by reducing the effect of those two factors. Possibilities of finding an actual method to reduce the effect of the above two factors are discussed.

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Carrier confinement performance by multiple quantum barriers (MQB) is demonstrated in 1.55 μm strained GaInAs/AlGaInAs multiple quantum well (MQW) lasers grown by molecular beam epitaxy. The strained MQW lasers with MQB at p-side optical confinement layer show larger characteristic temperature and slope efficiency at high temperature than those without MQB. It is also shown that the MQW lasers with MQB have less spontaneous emission from the optical confinement layer than the lasers without MQB. As another important result, it is demonstrated for the first time that the MQW lasers with MQB have less dependency of the K factor on the temperature than the lasers without MQB. These results further verify the effective carrier confinement performance of GaInAs/AlInAs MQB structure.

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Articles you may be interested inInvestigation of the optical properties of InGaAsN ∕ GaAs ∕ GaAsP multiple-quantum-well laser with 8-band and 10-band k · p modelThe effect of nonparabolicity of conduction band on the electron reflection spectrum of multiquantum barriers ͑MQB͒ has been examined. Drastic reduction in the effective barrier height is expected by adopting the nonparabolic model on the MQB which had been designed using the parabolic model for 1.5 m semiconductor lasers ͑LDs͒. The predicted enhancement in barrier height by the MQB is over 600 meV under parabolic model. However, it decreases to 40 meV under nonparabolic model with the same structure. On the other hand, the experimental enhancement in barrier height by the MQB is estimated to be around 30 meV on 1.5 m LDs, close to the value calculated by nonparabolic model. Those results suggest that a much higher effective barrier height can be realized by optimizing the MQB design taking the nonparabolicity into account. The conduction band nonparabolicity was incorporated by the k•p perturbation method.