In this paper the recent development on manufacturing and characterization of low dark currents p+-on-n HgCdTe photodiodes was presented.The n-Type HgCdTe (MCT) absorber layer was grown by liquid-phase epitaxy (LPE) on lattice matched CdZnTe (CZT) substrate and the P type layers are grown by As Ion plantation and vertical LPE (VLPE) from Hg-rich melts doped with arsenic.It is desirable that the MCT detectors can operate at high operating temperatures (HOT) without sacrificing their performance.We present our latest results on the standard n-on-p(Hg vacancy doped),ion implantation of arsenic and heterostructure p-on-n photodiode technology was selected for detailed HOT testing.The results prove that the performance of p-on-n photodiode is better than other devices at high operating temperatures.