包括第一半导体材料之信道区域的单晶FET系被设置于基板上方。当遮罩(例如闸极堆栈或牺牲闸极堆栈)正覆盖着该信道区域时，杂质掺杂的组成上渐变的半导体成长，例如于该信道区域之至少汲极端上，以引入载子阻隔传导带偏移及/或较宽的带隙于该晶体管之该汲极区域内。于一些实施例中，该组成上渐变招致至少0.25eV之载子阻隔带偏移。该较宽的带隙及/或带偏移贡献至降低的闸极感应汲极漏电(GIDL)。该杂质掺杂的半导体可从逆行的组成在组成上渐变至提供良好欧姆接触之合适的窄带隙材料。于一些实施例中，该杂质掺杂的组成上渐变的半导体成长系被集成至闸极最后(gate-last)、源极/汲极再成长finFET制程中。

Monolithic FETs including a channel region of a first semiconductor material disposed over a substrate. While a mask, such as a gate stack or sacrificial gate stack, is covering the channel region, an impurity-doped compositionally graded semiconductor is grown, for example on at least a drain end of the channel region to introduce a carrier- blocking conduction band offset and/or a wider band gap within the drain region of the transistor. In some embodiments, the compositional grade induces a carrier-blocking band offset of at least 0.25 eV. The wider band gap and/or band offset contributes to a reduced gate induced drain leakage (GIDL). The impurity-doped semiconductor may be compositionally graded back down from the retrograded composition to a suitably narrow band gap material providing good ohmic contact. In some embodiments, the impurity-doped compositionally graded semiconductor growth is integrated into a gate-last, source/drain regrowth finFET fabrication process.