Effects of Ar vs. O2 ambient on pulsed-laser-deposited Ga-doped ZnO

✍ Scribed by Robin C. Scott; Kevin D. Leedy; Burhan Bayraktaroglu; David C. Look; Yong-Hang Zhang

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 478 KB
• Volume: 324
• Category: Article
• ISSN: 0022-0248
• DOI: 10.1016/j.jcrysgro.2011.03.002

✦ Synopsis

Ga-doped ZnO films were deposited by pulsed laser deposition (PLD) at 200 1C and 10 mTorr in either pure argon (Ar films) or in oxygen (O 2 films). The bulk resistivity of the Ar films is o 2 Â 10 À 4 O cm at 300 K, two orders of magnitude lower than that of the O 2 films. In the Ar films, the donor concentration N D as determined by a detailed Hall-effect analysis is close to 100% of the total Ga concentration [Ga] measured by secondary ion mass spectrometry (SIMS), while in the O 2 films N D is less than 50% of [Ga]. Furthermore, the compensation ratio K ¼N A /N D is 4 90% for the O 2 films and o 60% for the Ar films. Yet, when the oxygen pressure is reduced to 0.2 mTorr, the O 2 films have resistivities of about 5 Â 10 À 4 O cm, approaching those of the Ar films. These results suggest that oxygen-rich environments produce Ga/O complexes that reduce the dopant activation efficiency and thus decrease N D and increase K. Some of these complexes may also contribute to the increase in deep centers observed in photoluminescence.