Electrical properties of high-quality stacked CdTe/photo-enhanced native oxide for HgCdTe passivation

A novel surface treatment method for obtaining a high-quality CdTe/HgCdTe interface is proposed. By stacking photoenhanced native oxide and CdTe films, we successfully passivated HgCdTe. This technique is advantageous because photoenhanced native oxides can form an excellent interface and adhere to HgCdTe substrate well. Using this novel technique, we have fabricated metal/CdTe/photoenhanced native oxide/HgCdTe structured metal-insulator-semiconductor (MIS) capacitors. From capacitance-voltage (C-V) measurement, we found that the flat-band voltage of such a MIS capacitor is about -0.2V with a fixed oxide charge of 1 × 10¹⁰ cm^-2. For comparison, conventional metal/CdTe/HgCdTe structured MIS capacitors were also fabricated. We found that capacitors with the photoenhanced native oxide layer have a much lower leakage current. Such a marked leakage current reduction is due to the good interfacial properties between the photoenhanced native oxide and the HgCdTe substrate.