Mechanism of Zn passivation in AlGaInP layer grown by metalorganic chemical vapor deposition

Abstract

The mechanism of passivation effect on the hole concentration in Zn-doped (Al 0.7Ga 0.3) 0.5In 0.5P layers grown by metalorganic chemical vapor deposition (MOCVD) is investigated. It is found that oxygen concentration in AlGaInP should be suppressed under 5 x 10 16 cm -3 in order to make the passivation behavior clear without effect of oxygen contamination, which was controlled by employing a high-grade gas purifier. The passivation of zinc acceptors has been effectively avoided by optimizing of the cooling atmosphere. The hole concentration increased with raising the AsH 3 flow stopping temperature after growth and it saturated at above 500°C. High hole concentration (beyond 1 x 10 18 cm -3) was achieved by combining the anti-passivation technique and the oxygen control techniques. We suggest from the hole concentration dependence on the measuring temperature that the new deep acceptor level due to the Zn passivation causes the hole concentration reduction in the AlGaInP layer.