In this paper, a physically based two-dimensional analytical model of potential profile is proposed for both symmetric and asymmetric p-type-doped Double Gate Junctionless Field Effect Transistors (DG JLFETs). The proposed model keeps its validity in the subthreshold region. In order to establish the model, 2-D Poisson's equation is solved in the channel region while assuming cubic potential distribution along the channel region. We also propose a 2-D analytical model of symmetric Double Gate Stack-Oxide Junctionless Field Effect Transistors (DGS JLFETs). In order to check out the validity of our proposed model, we have used SILVACO ATLAS simulator. Comparison of potential distribution is made between different structures. Between symmetric and asymmetric structures, symmetric structure shows better potential profile as they have shown higher potential distribution in channel region. But when DG JLFET is compared with DGS JLFET, we find better potential profile distribution in DGS JLFET. Important performance parameters like Ion/Ioff ratio, SS, DIBL, Threshold Voltage, IāV characteristics for different structures are found out and compared among them. Asymmetric structure with same electrode materials in both gates but having lower bottom gate oxide thickness showed better performances like higher Ion/Ioff ratio, lower SS, less DIBL compared to other DG JLFETs with and without stack oxide. [ABSTRACT FROM AUTHOR]