Superconducting nanowire single-photon detectors (SNSPDs) are very promising as integrated detectors for future quantum photonic integrated circuits. In this work, main technological challenges for the integration of NbN based SNSPDs onto GaAs based phonic circuits are addressed. A new approach to improve the performance of meander style SNSPDs based on a variable thickness is introduced and the first full integration of a quantum photonic chip on a scalable monolithic platform is demonstrated.