【Epitaxy Papers】Evidence of micrometer-scale ion damage in (010), (110), and (011) β-Ga₂O₃ epitaxial layers

      Researchers from University of California Santa Barbara have published a dissertation titled " Evidence of micrometer-scale ion damage in (010), (110), and (011) β-Ga₂O₃ epitaxial layers " in Applied Physics Letters.

Abstract

      We report the experimental observation of charge depletion up to 11.5 μm deep in (010), (110), and (011) β-Ga₂O₃ epitaxial layers due to ion damage from sputtering and inductively coupled plasma (ICP) etching processes, whereas charge depletion in (001) β-Ga₂O₃ epitaxial layers was minimal. The orientation-dependent reduction in C–V-measured charge density was first observed in NiO_x reactively sputtered heterojunction p–n diodes (HJDs). When compared to reference low-damage Schottky barrier diodes (SBDs), the sputtered HJDs showed a 9.4× increase in the specific on resistance (R_on,sp) and an 85% reduction in net donor concentration (N_D − N_A) at zero bias for sputter-damaged HJDs on (010) epitaxial layers, whereas HJDs on (001) remained unchanged. Similarly, sputtered SiO₂ caused a reduction in N_D − N_A, extending 11.5 μm into the (010) material. Next, SBDs were fabricated on β-Ga₂O₃ surfaces previously etched via a BCl₃ based ICP process and compared to SBDs on un-etched surfaces. The (010) SBDs on etched surfaces exhibited a 7.7× increase in R_on,sp and a 91% reduction in N_D − N_A at zero bias, whereas the (001) etched diodes exhibited little change. Additionally, (110) and (011) diodes fabricated on ICP damaged surfaces also showed an ∼82% reduction in N_D − N_A at zero bias, indicating that the (110) and (011) orientations are also susceptible to ion damage. Damage in the (010), (110), and (011) diodes is potentially caused by energetic ions that travel into the open channels present along the [010] direction and create compensating point defects, which could potentially diffuse further.

DOI：

https://doi.org/10.1063/5.0340749