[en] Electrical analysis of interfaces of (100)Si, (100)InP, and (100)In_0.53Ga_0.47As with TaSiO_x (Ta/Si≈1) films atomic-layer deposited using SiCl₄, TaCl₅, and H₂O precursors suggests Ta silicate as a good insulating and surface passivating layer on all three semiconductors. However, when a positive voltage is applied to the top metal electrode in a metal/ TaSiO_x /semiconductor configuration, considerable hysteresis of the capacitance-voltage curves, both at 300 and 77 K, is universally observed indicating electron injection and trapping in the insulator. To shed some light on the origin of this charge instability, we analyzed interface band alignment of the studied interfaces using the spectroscopies of internal photoemission and photoconductivity measurements. The latter reveals that independently of the semiconductor substrate material, TaSiO_x layers exhibit a bandgap of only 4.5±0.1 eV, typical for a Ta₂O₅ network. The density of electron states associated with this narrow-gap network may account for the enhanced electron injection and trapping. Furthermore, while a sufficiently high energy barrier for electrons between Si and TaSiO_x (3.1±0.1 eV) is found, much lower IPE thresholds are encountered at the (100)InP/TaSiO_x and (100) In_0.53Ga_0.47As/TaSiO_x interfaces, i.e., 2.4 and 2.0 eV, respectively. The lower barrier may be related by the formation of narrow-gap In-rich interlayers between A_IIIB_V semiconductors and TaSiO_x.