Avalanche photodiodes are widely used in optical receivers for high-speed communication systems. We have been studying the material AlGaAsSb (lattice-matched to InP substrates) experimentally in recent years, evaluating its potential as an alternative avalanche material for these avalanche photodiodes. Our experimental studies cover key characteristics relevant to high-speed avalanche photodiodes. The data obtained show that the material AlGaAsSb has higher gain-bandwidth product, lower excess noise factors, and weaker temperature dependence, compared to current avalanche materials such as InP and InAlAs.