Ordinary CCD type chips or photodiodes will likely lack sufficient sensitivity.
The corresponding semiconductor devices are Avalanche Photodiodes.
These have sufficient sensitivity and gain factor and they're pretty reasonably priced. But their typical size/ collection area is small, so you'd need a specialized optic to collect light from the scintillator. They also need a high supplied voltage, like PMT's.
Applications for scintillator detectors are usually gamma ray, x-ray, and neutron detection.
I don't think you will get sufficient gains from using a phone to detect scintillation light, but if ionization occurs within the camera chip itself you can detect it. There is active research on trying to make a cosmic ray observatory by using networks of smartphones. You can read more about it [here](https://arxiv.org/pdf/1410.2895.pdf). Fig.5 actually shows a picture of muons leaving tracks in a phone camera when it was exposed to a test beam at CERN.