The properties of III-V compound semiconductors and their heterojunctions have been relentlessly investigated due to their wide-ranging applications in electronic and optoelectronic technologies. One of most important electronic property of heterojunctions is the band offset which describes the relative alignment of the electronic bands across the junction interface. Accurate determination of band offsets is critical for understanding quantum transport properties of the heterojuncton. For many III-V materials systems, the band offset has been carefully measured experimentally.[1]