Volume 89, Issue 7, 01 April 2001
Index of content:
89(2001); http://dx.doi.org/10.1063/1.1352673View Description Hide Description
We have studied the linewidth around threshold of the lasing and nonlasing polarization mode (x and y) in a oxide-confined vertical-cavity semiconductor laser(VCSEL). We experimentally demonstrate: (i) that the nonlasing mode shows surprising behavior when the lasing mode passes through threshold, and (ii) that the polarizationfluctuations in a VCSEL are limited by the same quantum noise that sets its finite Schawlow–Townes linewidth.
89(2001); http://dx.doi.org/10.1063/1.1350616View Description Hide Description
Self-assembled InAs quantum dots(QDs) have been grown by solid-sourcemolecular beam epitaxy on a InP substrate. Transmission electron microscopy clearly shows that a high density of smaller InAs islands can be obtained by using such a high index substrate. After introducing a lattice-matched underlying layer, the InAs QDs are much more uniform in size and form two-dimensional well ordered arrays. The photoluminescence (PL) spectra also confirm that the InAs QDsgrown on underlying have a better quality than those grown in the matrix. A simple calculation indicates that the redshift of the PL peak energy mainly results from InAs QDs on underlying of large size.
89(2001); http://dx.doi.org/10.1063/1.1352674View Description Hide Description
In this article we report results on the physical properties of defect levels generated by high-field stress in silicon dioxide. Carrier separation experiments were performed in p-channel metal–oxide–semiconductor transistors,measuring the transient and steady-state leakage currents. Different transient behaviors are observed in the channel and substrate currents, indicating that different kinds of traps are involved in the transient and steady-state leakage currents. This conclusion is also supported by time-relaxation experiments, where it is shown that the components of the current feature different relaxation behaviors. The impact of these results on the modeling of stress-induced leakage conduction is also addressed.
89(2001); http://dx.doi.org/10.1063/1.1343517View Description Hide Description
An approach to model noise in the weak inversion range of metal–oxide–semiconductor transistors (MOST) is proposed, based on Hooge’s theory (mobility fluctuation model). Starting from conduction equations in the subthreshold regime, a method to evaluate the total number of carriers under the gate is presented and allows us to deduce the Hooge parameter This model is applied to MOSTs. With the proposed model, the value of obtained in weak inversion is quite similar to this extracted in strong inversion allowing a unique description of the noise.
Effect of emitter metallization on thermal properties of small AlGaAs heterojunction bipolar transistors89(2001); http://dx.doi.org/10.1063/1.1352672View Description Hide Description
We have extended an experimental technique to measure thermal resistance by pulsed current–voltage measurements to small bipolar transistors with thermal time constants of several hundred nanoseconds. Results for a 3×3 AlGaAs/GaAs heterojunctionbipolar transistor are compared with detailed finite element method simulations, and show good agreement when heat flow into the emitter metallization is accounted for. Simulation results indicate that emitter metallization plays a significant role in reducing temperature nonuniformity across the emitter.