We analyzed the properties of the two factors determining the resonant-tunneling transport: the one- dimensional carrier energy distribution factor, which monotonically decreases with energy and increases with temperature, and the transmission probability peak, which decreases with bias and temperature, and we determined a criterion for current resonance. Our conclusions are quite different from those in commonly used descriptions. Calculations of the resonant tunneling versus temperature with constant E F , μ, and m * cannot give a decrease of peak currents with temperature