Avalanche multiplication process in avalanche transit time devices results in large number of electrons-hole pairs (EHPs). Therefore, there is considerable temperature rise in the junction. This high temperature than normal operating one, leads to large space charge effects by creating extra space charges. As a result, practical efficiency of transit time devices is below 30%. It is quite important to understand the effects of space charges on device performances. The space charge effect is computationally studied and analysed here for the graphene material based double drift region (DDR) impact ionization and avalanche transit time (GIMPATT) diode. Also, the effect in GIMPATT is compared with IMPATT based on other material like Si, Ge, GaAs, WzGaN, InP, 4H–SiC.

雪崩渡越时间设备中的雪崩倍增过程导致大量的电子-空穴对（EHP）。因此，结中有相当大的温度升高。这种比正常运行温度高的温度会通过产生额外的空间电荷而导致较大的空间电荷效应。结果，渡越时间设备的实际效率低于30％。了解空间电荷对设备性能的影响非常重要。对于基于石墨烯材料的双漂移区（DDR）碰撞电离和雪崩渡越时间（GIMPATT）二极管，此处通过计算研究和分析了空间电荷效应。此外，将GIMPATT中的效果与基于其他材料（例如Si，Ge，GaAs，WzGaN，InP，4H–SiC）的IMPATT进行了比较。