Semiconductor laser device and method of fabricating semiconductor laser

Abstract

In a semiconductor laser device including a stack of semiconductor laser chips, each semiconductor laser chip includes opposite upper and lower surfaces, an upper electrode disposed on a portion of the upper surface, and a lower electrode disposed on a portion of the lower surface. Two adjacent semiconductor laser chips in the stack are connected such that the lower electrode of an upper laser chip is bonded to the upper electrode of a lower laser chip with solder. Since the upper electrode (lower electrode) is disposed on a portion of the upper surface (lower surface) of each laser chip, i.e., it is not disposed over the entire upper surface (lower surface) of the laser chip, the solder hardly flows over the side surface of the laser chip, so that unwanted short-circuiting between the upper electrode and the lower electrode of the laser chip is avoided. In addition, when solder is molten between two electrodes, the molten solder spreads over the surfaces of the electrodes, and the surface tension of the molten solder draws the electrodes to each other so that the electrodes are automatically aligned with each other. Therefore, in this stacked laser device, since the surface tension of the molten solder functions between the upper electrode and the lower electrode of the adjacent laser chips, automatic alignment is performed between these laser chips.