ZnO Schottky Nanodiodes Processed From Plasma-Enhanced Atomic Layer Deposition at Near Room Temperature

• Published in: IEEE transactions on electron devices Vol. 65; no. 10; pp. 4513 - 4519
• Main Authors: Shen, Mei, Muneshwar, Triratna P., Cadien, Kenneth C., Tsui, Ying Yin, Barlage, Douglas W.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aluminum; Atomic layer epitaxy; Electrodes; Hybrid circuits; Hybrid system integration; Hybrid systems; II-VI semiconductor materials; low thermal budget process; Metallizing; Plasma temperature; plasma-enhanced atomic layer deposition (PEALD); Production methods; Room temperature; Schottky diodes; Schottky formation mechanisms; Schottky nanodiode; Substrates; Thickness; Thin films; X-ray scattering; Zinc oxide
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2018.2866598

In this paper, we report a low thermal budget manufacturing method to produce highly rectifying Schottky diodes with ultrathin ZnO films grown at near room temperature by plasma-enhanced atomic layer deposition. A bottom Schottky electrode with Pt and a top ohmic electrode with Al/Au stacks were used for metallization. The resultant diodes demonstrated high rectifying ratios on the order of 10 6 , relatively low ideal factor <inline-formula> <tex-math notation="LaTeX">{n} </tex-math></inline-formula> values of 1.36 ±0.05, effective Schottky barrier height <inline-formula> <tex-math notation="LaTeX">\Phi _{B} </tex-math></inline-formula> values of 0.77 ± 0.01 eV, and high breakdown fields of 1.67 MV/cm extrapolated from the current-voltage (<inline-formula> <tex-math notation="LaTeX">{I} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">{V} </tex-math></inline-formula>) characteristics at room temperature. These specifications are among the best-reported performance of Schottky diodes with ZnO thin films in nanoscale thickness. The interface at the Schottky contacts was investigated and revealed a lateral nonuniform distribution of interface defect states. A modified Richardson plot was used to deduce a mean barrier height (<inline-formula> <tex-math notation="LaTeX">\overline {\Phi }_{B{0}} </tex-math></inline-formula>) of 1.25 ± 0.1 eV and an apparent Richardson constantc (<inline-formula> <tex-math notation="LaTeX">{A}^{\ast \ast } </tex-math></inline-formula>) of 11.64 A/cm 2 /K 2 . In addition, <inline-formula> <tex-math notation="LaTeX">{I} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">{V} </tex-math></inline-formula> characteristics of the diodes were observed to improve with aging. This newly developed, low thermal budget technique of ZnO Schottky nanodiodes is attractive for hybrid circuit systems and polymer electronics with integration constraints.