A kind of epitaxial structure of dfb laser and its preparation method

Abstract

The invention discloses an epitaxial structure of a DFB laser, comprising an InP substrate, on which a buffer layer, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper confinement layer are sequentially arranged from bottom to top , a second buffer layer, an corrosion barrier layer, a cladding layer and a grating layer; a secondary epitaxial layer is arranged on the grating layer, and the secondary epitaxial layer includes a grating cladding layer, a barrier gradient layer and an ohmic contact layer from bottom to top , the grating cladding layer includes a grating covering layer and a transition layer, and the thickness of the grating covering layer is greater than the thickness of the grating layer. The present invention also discloses a method for preparing the epitaxial structure of the above-mentioned DFB laser. The grating covering layer is grown at a low temperature and pulsed at a slow speed, and PH3 gas of 850 sccm-950 sccm is introduced at the same time to suppress volatilization of the grating layer P; the transition layer adopts high temperature, grow fast. The invention can prevent the grating layer from being etched, improve the epitaxial structure quality of the DFB laser, and reduce the application cost of the DFB laser.

Description

technical field [0001] The invention relates to the technical field of DFB laser manufacturing, in particular to an epitaxial structure of a DFB laser and a preparation method thereof. Background technique [0002] The optical communication network uses light as the carrier of signal transmission. Compared with the electrical communication network using copper cables as the transmission medium, the speed, capacity and anti-interference ability of information interconnection have been significantly improved, so it has been widely used. Semiconductor lasers are the main light sources for optical communication networks, including Fabry-Perot lasers (FP lasers), distributed feedback lasers (DFB) and vertical cavity surface emitting lasers (VCSEL). Among them, the DFB laser establishes a Bragg grating inside the semiconductor, and relies on the distribution feedback of light to realize the selection of a single longitudinal mode. In the current range, the mode hopping of ordinar...

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Problems solved by technology

In addition, lattice changes can lead to a high density of point defects on the device surface, deteriorating device performance

[0004] In order to prevent P volatilization from being taken away by the carrier gas and prevent the grating layer from being etched during the heating and high-temperature growth process before the secondary growth, a low-temperature (usually growth temperature is not higher than 550°C) process is used in the prior art to grow the secondary Epitaxial layer to avoid etching of the grating, but the material quality of the secondary epitaxial layer grown at low temperature is poor, which will also affect the performance of DFB

The growth conditions of the secondary epitaxial layer of DFB grown by MOCVD are very harsh, resulting in low DFB production yield and high production and application costs.

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