Photoluminescence (PL) of selectively grown phosphorus (P) doped germanium (Ge) is investigated. 350–600nm thick P-doped Ge is grown on 100nm thick P-doped Ge buffer layer, which is annealed at 800°C before the main part of Ge deposition. In the case of Ge deposited at 325°C, approximately two times higher PL intensity is observed by P doping of ~3.2×1019cm−3. Further increase of PL intensity by a factor of 1.5 is observed by increasing the growth temperature from 325°C to 400°C due to improved crystal quality. Varying PH3 partial pressure at 400°C, red shift of the PL occurred with increasing P concentration due to higher bandgap narrowing. With increasing P concentration up to ~1.4×1019cm−3 at 400°C the PL peak intensity increases by filling electrons into the L valley and decreases due to enhanced point defect concentration and degraded crystallinity. By post-annealing at 500–800°C, the PL intensity is further increased by a factor of 2.5 because of increased active P concentration and improved crystal quality. Reduced direct bandgap energy by introducing tensile strain is also observed.