Leaky characteristic in a leaky integrate-and-fire (LIF) neuron is important to prevent a permanent effect on a single input stimulus in an artificial neuromorphic system as well as a biological nerve. In a proposed single-transistor-based LIF neuron (1T-neuron), band-to-band tunneling (BTBT) dominates the leaky characteristic. Three methods to control the leaky characteristic of a 1T-neuron are demonstrated in this work: controlling the relative location of the drain junction edge to a gate, tuning the gate voltage ( ${V}_{G}$ ), and modulating body doping concentration ( ${N}_{sub}$ ). The 1T-neuron becomes leakier with a more overlapped drain junction with the gate, decreased ${V}_{G}$ , and increased ${N}_{sub}$ by accelerating the BTBT.