                \begin{tikzpicture}
                        \node[circle,fill,minimum size=0.2cm,inner sep=0,opacity=0.5] at (0.25,1) {};
                        \draw[opacity=0.5] (0.25,1) -- ++(-1,0);
                        \node[circle,fill,minimum size=0.2cm,inner sep=0,opacity=0.5] at (3.75,1) {};
                        \draw[opacity=0.5] (3.75,1) -- ++(1,0);

                        \draw[draw=none,fill=red,opacity=0.4] (0,0) -- ++(0,2) -- ++(0.5,0) --++(0,-2) -- ++(-0.5,0) -- cycle;
                        \draw[draw=none,fill=red,opacity=0.4] (3,0) -- ++(0,2) -- ++(0.5,0) --++(0,-2) -- ++(-0.5,0) -- cycle;
                        \draw[draw=none,fill=blue,opacity=0.4] (0.5,0) -- ++(0,2) -- ++(2.5,0)-- ++(0,-2) -- ++(-2.5,0) -- cycle;
                        
                        \draw[fill=red,opacity=0.4] (0,2) --++(0.5,0.25) -- ++(0.5,0) -- ++(-0.5,-0.25) -- cycle;
                        \draw[fill=red,opacity=0.4] (3,2) --++(0.5,0.25) -- ++(0.5,0) -- ++(-0.5,-0.25) -- cycle;
                        \draw[fill=blue,opacity=0.4] (0.5,2) --++(0.5,0.25) -- ++(2.5,0) -- ++(-0.5,-0.25) -- cycle;
                        
                        \draw[fill=red,opacity=0.4] (3.5,2) -- ++(0.5,0.25) -- ++(0,-2) -- ++(-0.5,-0.25) --cycle;
                        
                        \node[anchor=south] at (0.25,2) {P};
                        \node[anchor=south] at (3.25,2) {N};
                        \node[anchor=south] at (1.75,1) {depletion};
                        
                        \draw[dashed] (1.75,0) -- ++(0,2) -- ++(0.5,0.25);
                        
                        \draw[latex-latex] (0.5,-0.25) -- (3,-0.25);
                        \node[anchor=north] at (1.75,-0.25) {$W$};
                        
                        \node at (4.5,2.5) (a) {$A$};
                        \draw[-triangle 45] (a.south west) -- (3.75,1.75);
                \end{tikzpicture}
