| 摘要 |
PURPOSE:To improve characteristics such as a threshold current value and light emitting efficiency, by arranging projections, which comprise a second semiconductor material and form parallel lines, in contact with a substrate or a semiconductor layer comprising a first semiconductor material, depositing a waveguide layer comprising a third semiconductor material thereon, thereby enhancing the feedback rate of a diffraction grating. CONSTITUTION:On the 100 surface of an N-type InP substrate 1, an InGaAsP layer 2 is grown by liquid phase epitaxy (LPE) and the like. Positive type photoresist, which is applied on the N-type InGaAsP layer 2, is exposed by a two-beams interference method. A resist mask 11 is formed by development. The InGaAsP layer 2 is selectively etched with respect to the InP substrate 1, and projections 2A comprising InGaAsP of lambdag=1.1mum are formed in parallel lines. The resist mask 11 is removed, and semiconductor layers of a wave filtering layer 3, an active layer 4, a clad layer 5 and a cap layer 6 are formed by the LPE method and the like. A P-type electrode 8, and an N-side electrode 9 are arranged on the active layer of the semiconductor substrate. Chip dividing, end-surface treatment and the like are performed, and a DFB laser element is completed. |
