Stability against hydrogen plasma exposure of Al‐doped zinc oxide thin film for a‐Si thin film solar cell

Abstract

In this study, the stability of Al‐doped zinc oxide (AZO) films under hydrogen (H2) plasma exposure was investigated. The plasma power was varied from 60 to 300 W, and the exposure time was also varied from 10 to 60 min to investigate the stability of the films against H2 plasma. Surface morphologies of the AZO films did not change much after H2 plasma exposure. The average optical transmittance was 87.4% at a plasma power of 60 W and decreased to 70.9% when the plasma power was 300 W. The electrical properties, including mobility and resistivity, were improved by plasma treatment. The characteristics of AZO films after H2 plasma exposure showed negligible differences in morphology and improved optical and electrical properties, which implies that the prepared AZO films have a strong resistance to H2 plasma exposure up to an RF power of 60 W for 20 minutes. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Stability study: Transparent conducting oxides in chemically reactive plasmas

“…Blue shift in the transmittance spectra of AZO films is ascribed to shift in the fermi level closer to conduction band leading to band broadening with increasing concentration of the carriers. This is often termed as Burstein-Moss effect [20]. Instability of ITO and FTO are discussed earlier with several mechanisms occurring during H-Plasma.…”

“…This is the key requirement for an ideal TCO. H + ions impinging over the surface of the AZO thin film emerging out from the plasma passivates various defects by electron transfer within the material leading to the growth of grain size [20], [21]. Along with optical and electrical analyses, instability of FTO and ITO are further understood with an aid of OES spectra.…”

Expanding Thermal Plasma Deposition of Al‐Doped ZnO: On the Effect of the Plasma Chemistry on Film Growth Mechanisms

“…Intrinsic ZnO has a direct optical band‐gap at ∼ 3.37 eV (∼ 370 nm), and when doped (most commonly with group III elements such as Al, B, or Ga) can exhibit resistivities as low as 8 · 10 −5 Ω · cm . ZnO is relatively abundant, may be easily fabricated by various dry and wet methods, is structurally stable under hydrogen plasma exposure, and can be chemically stable up to 700 °C . Films of Al‐doped ZnO (ZnO:Al) have been generated by sputtering, pulsed laser deposition (PLD), sol‐gel methods, atomic layer deposition (ALD) and various types of chemical vapour deposition (CVD) .…”