Patent ID: 7659137

Claim:
A fabrication method of fabricating a structure that is usable to generate or detect THz electromagnetic radiation, the method comprising: a forming step of forming a GaAs epitaxial layer containing arsenic cohesions on a GaAs substrate at a substrate temperature below about 300° C.; a first heating step of heating the GaAs substrate with the GaAs epitaxial layer in an ambience containing arsenic at a substrate temperature in a range from 600° C. to 800° C., after the forming step; and a second heating step of heating the GaAs substrate with the GaAs epitaxial layer at a substrate temperature in a range from 700° C. to 800° C. in a hydrogen-gas or an inert-gas ambience, after the first heating step, wherein, when the second heating step is performed at a temperature of about 700° C., an average diameter of the arsenic cohesions is about 13 nm and an average interval distance between centers of the arsenic cohesions is about 55 nm, and, when the second heating step is performed at a temperature of about 800° C., the average diameter of the arsenic cohesions is about 22 nm and the average interval distance between the centers of the arsenic cohesions is about 80 nm.