Abstract: A VCSEL having an N-type Bragg mirror with alternating layers of high bandgap (low index) and low bandgap (high index) layers of AlGaAs. The layers may be separated by a step change of Al composition followed by a graded region, and vice versa for the next layer, in the N-type mirror to result in a lower and more linear series resistance. Also, an N-type spacer layer may be adjacent to an active region of quantum wells. There may be a similar step in a change of Al composition from the nearest layer of the N-type mirror to the N-type spacer formed from a lower bandgap direct AlGaAs layer to provide lower free carrier absorption. With electron affinity engineering, a minority carrier hole barrier may be inserted adjacent to the quantum wells to improve hole confinement at high current density and high temperature.

Abstract: Systems for wafer level burn-in (WLBI) of semiconductor devices (210, 215) are presented. Systems having at least two electrodes for the application of electrical bias and/or thermal power on each side of a wafer (100) having back (105) and front (110) electrical contacts for semiconductor devices borne by the wafer (100) is described. Methods of wafer level burnin using the system are also described. Furthermore, a pliable conductive layer (220) is described for supplying pins or contacts (110) on device side of a wafer with electrical contact. The pliable conductive layer (220) can allow for an effective series R in each of the devices borne by the wafer (100), thus helping keep voltage bias level consistent. The pliable conductive layer can also prevent damage to a wafer when pressure is applied to it by chamber contacts (210, 215) and pressure onto surfaces of the wafer (100) during burn-in operations.

Abstract: Optical transmitters are disclosed, one example of which includes a vertical cavity surface emitting laser that includes a substrate upon which a lower mirror is disposed. In this example, a spacer is disposed between the lower mirror and an active region. Another spacer separates the active region and an upper mirror. The upper mirror includes an oxide insulating region that is damaged by ion implantation so that desirable effects are achieved with respect to lateral sheet resistance, and quantum well recombination centers in the active region.