\tikzset{
  % bands
  sc band con/.style={   draw=fg0, thick},
  sc band val/.style={   draw=fg0, thick},
  sc band vac/.style={   draw=fg1, thick},
  sc band/.style={       draw=fg0, thick},
  sc fermi level/.style={draw=fg-aqua,dashed,thick},
  % electron filled
  sc occupied/.style={
    pattern=north east lines,
    pattern color=fg-aqua,
    draw=none
  },
  % materials
  sc p type/.style={     draw=none,fill=bg-yellow!20},
  sc n type/.style={     draw=none,fill=bg-blue!20},
  sc metal/.style={      draw=none,fill=bg-purple!20},
  sc oxide/.style={      draw=none,fill=bg-green!20},
  sc separate/.style={   draw=fg0,dotted},
}

\newcommand\drawDArrow[4]{
    \draw[<->] (#1,#2) -- (#1,#3) node[midway,right] () {#4};
}
% Band bending down at L-R interface: BendH must be negative
% need two functions for different out= angles, or use if else on the sign of BendH
\newcommand\leftBandAuto[2]{
  \directlua{
    if \tkLBendH == 0 then
      tex.print([[(\tkLx,#2) \ifblank{#1}{}{node[anchor=east] \detokenize{{#1}}} -- (\tkLW,#2) ]])
    else
      if \tkLBendH > 0 then
        angle = 180+45
      else
        angle = 180-45
      end
      tex.sprint([[(\tkLx,#2) \ifblank{#1}{}{node[anchor=east] \detokenize{{#1}}}
        -- (\tkLW-\tkLBendW,#2) to[out=0,in=]], angle, [[](\tkLW,#2+\tkLBendH)]])
    end
  }
  % % \ifthenelse{\equal{\tkLBendH}{0}}%
  %   % {%
  %     \ifthenelse{\tkLBendH > 0}%
  %     {\pgfmathsetmacro{\angle}{-45}}%
  %     {\pgfmathsetmacro{\angle}{45}}%
  %   % }
}
\newcommand\rightBandAuto[2]{
  \directlua{
    if \tkRBendH == 0 then
      %-- tex.print([[\rightBand{#1}{#2}]])
    tex.print([[(\tkRx,#2) -- (\tkW,#2)]]) %-- \ifblank{#1}{}{node[anchor=west] \{#1\}}]])
    else
      if \tkRBendH > 0 then
        angle = -45
      else
        angle = 45
      end
      tex.sprint([[(\tkRx,#2+\tkRBendH) to[out=]], angle, [[,in=180] (\tkRx+\tkRBendW,#2) -- (\tkW,#2) ]])
        %-- \ifblank{#1}{}{node[anchor=west] \{#1\}} ]])
    end
    if "\luaescapestring{#1}" \string~= "" then
      tex.print([[node[anchor=west] \detokenize{{#1}} ]])
    end
  }
  % \ifthenelse{\equal{\tkRBendH}{0}}%
  %   {\rightBand{#1}{#2}}
  %   {%
  %     \ifthenelse{\tkRBendH > 0}%
  %     {\pgfmathsetmacro{\angle}{-45}}%
  %     {\pgfmathsetmacro{\angle}{45}}%
  %     (\tkRx,#2+\tkRBendH) to[out=45,in=180] (\tkRx+\tkRBendW,#2) -- (\tkW,#2) 
  %     \ifblank{#1}{}{node[anchor=west]{#1}} 
  %   }
}
\newcommand\leftBandDown[2]{
    (\tkRx,#2+\tkRBendH) to[out=45,in=180] (\tkRx+\tkRBendW,#2) -- (\tkW,#2) 
    \ifblank{#1}{}{node[anchor=west]{#1}} 
}
\newcommand\rightBandDown[2]{
    (\tkRx,#2+\tkRBendH) to[out=45,in=180] (\tkRx+\tkRBendW,#2) -- (\tkW,#2) 
    \ifblank{#1}{}{node[anchor=west]{#1}} 
}
% Band bending down at L-R interface: BendH must be positive
\newcommand\leftBandUp[2]{
    (\tkLx,#2) \ifblank{#1}{}{node[anchor=east]{#1}} 
    -- (\tkLW-\tkLBendW,#2) to[out=0,in=180+45] (\tkLW,#2+\tkLBendH) 
}
\newcommand\rightBandUp[2]{
    (\tkRx,#2+\tkRBendH) to[out=-45,in=180] (\tkRx+\tkRBendW,#2) -- (\tkW,#2) 
    \ifblank{#1}{}{node[anchor=west]{#1}} 
}
% Straight band
\newcommand\leftBand[2]{
    (\tkLx,#2) \ifblank{#1}{}{node[anchor=east]{#1}} -- (\tkLW,#2) 
}
\newcommand\rightBand[2]{
    (\tkRx,#2) -- (\tkW,#2) \ifblank{#1}{}{node[anchor=west]{#1}} 
}

\newcommand\drawAxes{
  \draw[->] (0,0) -- (\tkW+0.2,0) node[anchor=north] {$x$};
  \draw[->] (0,0) -- (0,\tkH+0.2) node[anchor=east] {$E$};
}

\newcommand\tkXTick[2]{
  \pgfmathsetmacro{\tickwidth}{0.1}
  \draw (#1, -\tickwidth/2) -- (#1, \tickwidth/2) node[anchor=north] {#2};
}
\newcommand\tkYTick[2]{
  \pgfmathsetmacro{\tickwidth}{0.1}
  \draw (-\tickwidth/2, #1) -- (\tickwidth/2,#1) node[anchor=east] {#2};
}