A substrate structure may be used in a display device. The substrate structure may include a base substrate, a transistor, and a silicon oxynitride layer. The transistor may include a semiconductor member and a gate electrode and may overlap the base substrate. The silicon oxynitride layer may directly contact at least one of the base substrate, the semiconductor member, and the gate electrode and may include (and/or contain) a hydrogen atom set. A hydrogen concentration in the silicon oxynitride layer may be greater than or equal to 1.52 atomic percent.