Method for making a semiconductor laser

• US 5,314,838 A
• Filed: 09/10/1992
• Issued: 05/24/1994
• Est. Priority Date: 12/14/1990
• Status: Expired due to Term

• Current Assignee: AT&T, Inc.
• Original Assignee: AT&T, Inc.
• Inventors: Wang, Yeong-Her, Tai, Kuochou, Chu, Sung-Nee G., Cho, Alfred Y.
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): Paladugu, Ramamohan Rao
• Application Number:
  US07/943,103
• Time in Patent Office: 621 Days
• Field of Search: 437/105, 437/107, 437/126, 437/129, 437/133, 437/946, 372/43, 372/44, 372/45, 372/46
• US Class Current: 438/32
• CPC Class Codes: H01S 5/18305 with emission through the substrate, i.e. bottom emission
• CPC Class Codes: H01S 5/18327 Structure being part of a DBR H01S5/18391 takes precedence
• CPC Class Codes: H01S 5/18375 based on metal reflectors
• CPC Class Codes: H01S 5/18377 comprising layers of different kind of materials, e.g. combinations of semiconducting with dielectric or metallic layers
• CPC Class Codes: H01S 5/3202 grown on specifically orientated substrates, or using orientation dependent growth
• CPC Class Codes: H01S 5/3203 on non-planar substrates to create thickness or compositional variations
• CPC Class Codes: H01S 5/32308 emitting light at a wavelength less than 900 nm
• CPC Class Codes: Y10S 117/902 Specified orientation, shape, crystallography, or size of seed or substrate
• CPC Class Codes: Y10S 438/973 Substrate orientation

Abstract

Disclosed is a method for manufacturing a vertical cavity, surface-emitting laser. The method includes growing a distributed Bragg reflector having at least 10 layers of alternating composition on a gallium arsenide substrate. The growth surface of the substrate is tilted by an angle of 1°-7° from the orientation of a (100) surface toward the orientation of a (111)A surface. This results in improved reflectivity of the DBR.

Claims

1. A method for manufacturing a vertical cavity, surface-emitting laser (to be referred to as a VCSEL), the method comprising the steps of providing a gallium arsenide substrate having approximately a (100) growth surface, epitaxially growing a distributed Bragg reflector (to be referred to as a DBR) on the growth surface, and performing at least one additional step toward completion of the VCSEL, CHARACTERIZED IN THAT

the growth surface is tilted by at least 1°

, and not more than about 7°

, from the orientation of a (100) surface toward the orientation of a (111)A surface;

the DBR comprises at least ten layers of alternating composition;

the DBR layers of alternating composition comprise, in alternation, Al_x Ga_1-x As and Al_y Ga_1-y As, wherein one of x and y is greater than 0.35, and the other of x and y is less than or equal to 0.35; and

during the step of epitaxially growing the DBR, the substrate temperature is less than 600°

C.

2. Method of claim 1, in which x is approximately equal to 1, and y is approximately equal to 0.1.

3. Method of claim 1, in which x is approximately equal to 0.1, and y is approximately equal to 0.7.

4. Method of claim 1, in which the VCSEL has a threshold current density of at most about 10.5 kA/cm².

5. Method of claim 1, in which the epitaxially growing step comprises growing the DBR by molecular beam epitaxy.

6. Method of claim 1, in which one of x and y is at least 0.7 and not more than 1.0, and the other of x and y is less than 0.7.

7. Method of claim 6, in which each layer of the DBR is grown by molecular beam epitaxy at a rate of at least 0.2 μ

m per hour.