YAlO3 thin films doped with different amounts of Er3+ have been grown directly onto (110) SrTiO3 substrate using the metal-organic chemical vapor deposition method (MOCVD). X-ray diffraction patterns and the rocking curve of the (002) reflection point to the growth of < 001 >-oriented YAlO3 phase. Piezo-spectroscopic (PS) biaxial calibration was performed on two luminescence bands, related to transitions from the S-4(3/2) excited state, using a specially designed ball-on-ring loading jig. Such a PS calibration allowed us to retrieve the rate of wavelength shift with stress without separating the grown film from the substrate. The outcome of the PS calibration has been applied to build up in the field emission scanning electron microscope (FEG-SEM) high-resolution maps of the residual stress field developed in the film. Results indicate that the residual stress in Er3+: YAlO3 films were compressive in nature and increased with increasing Er3+ dopant concentration.