Semiconductor laser device and its production method

A semiconductor laser device (100) includes a Zn-doped p type semiconductor substrate (1a) in which more than 81% of Zn dopant atoms are activated to produce carriers, and semiconductor layers epitaxially grown on the Zn-doped p type semiconductor substrate (1a), including an active layer (2a) sandwiched between n type and p type cladding layers (15a,11a). Therefore, during the epitaxial growth of the semiconductor layers, diffusion of inactive Zn atoms from the substrate (1a) to the semiconductor layers is reduced, with the result that the internal loss due to free carrier absorption in the active layer (2a) and the underlying p type cladding layer (11a) is reduced and non-radiative recombinations of carriers in the active layer (2a) are reduced.