Sensitivity of resonant tunneling diodes to barrier variation and quantum well variation: A NEGF study

A Non-Equilibrium Green’s Function (NEGF) simulation study on the impact of varying barriers and quantum well (QW) for a double barrier GaAs/Al${}_{\text{0.3}}$Ga${}_{\text{0.7}}$As Resonant Tunneling Diode (RTD) was carried out. This includes both variation of section thicknesses and the inclusion of interface roughness (IR) at different GaAs/Al${}_{\text{0.3}}$Ga${}_{\text{0.7}}$As interfaces. Narrower QWs and thinner symmetric barriers both resulted in a perturbation of Negative Differential Region (NDR) of the current–voltage (I-V) characteristic to greater bias. Asymmetric variation of the barriers controlled the perturbation of the resonant peak bias $V_r$, with a thinner first barrier resulting in a perturbation to greater bias and a thinner second barrier resulting in the inverse. Both barrier thicknesses inversely impacted the current, with the first barrier having a greater impact. The impact of IR was studied using the average of 25 device I-V characteristics for a given configuration of IR, as well as the I-V characteristic and charge density of specific devices. It was found that IR along the QW reduced the effective QW width and IR along the barriers increased their effective thickness, which together explained the effects of IR along all Al${}_{\text{0.3}}$Ga${}_{\text{0.7}}$As interfaces.