InP/GalnAsP double heterostructure laser diode with buried active layer, and method for its production

Claim 2

InP/GaInAsP laser diode containing a built-in isolating p-n junction with a double channeled double heterostructure carrier, comprising a buried active layer built up on an InP substrate, characterized in that on the orientated substrate (1) there are two parallel channels (9), between which channels (9) a buried GaInAsP active layer (3a) is arranged, which is confined on all sides by n and p type InP layers with a wide inhibiting zone and a low refractive index, that on the substrate (1) there is formed a n-type InP buffer layer (2) and thereon a further GaInAsP layer (3) with narrow gap and lying at the bottom of the channels (9) and on the planar parts, that thereon a further n-type layer (4) is arranged carrying a further n-type current-limiting layer (5), whereon an InP embedding layer (6) is provided on which a GaInAsP contact layer (7) of the p-type is arranged, while this one is covered with a multilayer p-side contact-metal layer (8a), advantageously of Au/AuZn, while on the other side of the carrier a n-side contact-metal layer (8b) is directly arranged, preferably consisting of AuGe/Ni/Au.

Claim 3

Method for producing a laser diode as claimed in claim 1 by using the method of liquid phase epitaxy, in the course of which orientation, photolithography, etching, liquid-­epitaxial enhancement, metallization and cleaving are used, characterized in that in the course of producing the laser structure, first of all the carrier is prepared in the following way: - an InP substrate is orientated by cleaving in the <110> crystallographic direction and by etching, then - an etching window parallel with the <110> crystallographical direction is opened by using photolithography, windows of the width of 4 µm are arranged in a distance of 6 µm, while the distance between the stripe-pairs amounts preferably to 400 µm, followed by - forming channels, expediently with a depth of 3-5 µm, by etching, using acidic acid, hydrogen bromide and O,1 N KMO₄ solution mixed in a proportion of 5:1:1, and - removing the photo-resistent laquers and cleaning the segment; that the pretreated InP substrate is put into the epitaxial reactor and the laser structure is prepared by using the one-step epitaxy so that the following layers are grown onto the InP carrier in the foIlowing order of sequence: - n-InP buffer layer (2), preferably 0,5-1 µm thick, with Sn 10¹⁸/cm³ dopant, - GaInAsP active layer (3a) undoped, preferably in a thickness of O,1-O,2 µm and Eg = 1,3 µm, - p-InP confining layer (4), preferably O,5-1 µm thick, Zn: 3-7 x 10¹⁷/cm³ as dopant, - n-InP current limiting layer (5), preferably in a thickness of O,5-1,5 µm, Te: 2-3 x 10¹⁸/cm³ as dopant - p-InP as embedding layer (6), preferably 2-4 µm thick, Zn: 5-8 x 10¹⁸/cm³ as dopant, - p⁺ Ga InAsP contact layer, thickness: preferably O,5µm, Eg = 1,03 µm; and that the wafer containing the laser structure grown in the described way, is thinned on the backside (17) preferably to 100-200 µm, and then, onto the p-side (16), a contact metal layer (8a), preferably of Au/AuZn is applied in a thickness of 200-1400 Å, while onto the n-side (17) a contact metal layer (8b) is applied, preferably AuGe/Ni/Au in a thickness of 3000/700/1000 Å by means of vaporization, whereafter the contact layers (8a,8b) are subjected to a heat treatment at 420 °C in a H₂ gas space, preferably for 10 seconds.