generated from kenryuS/report-temp
250 lines
11 KiB
TeX
250 lines
11 KiB
TeX
\section{理論}
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\subsection{ダイオード}
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ダイオードとは半導体の接合による電子の移動方向を制限する素子である.
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多くの場合, 単にダイオードと呼ばれるものは, 2種類の半導体を接合したpn接合ダイオードのことである.
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pn接合ダイオードとは正孔を多くもつp形半導体と自由電子が多いn形半導体を組み合わせたダイオードである.
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これら半導体を接合すると接合面と呼ぶ境界線で少数のn形半導体内の自由電子がp形半導体の正孔を埋める. この移動を拡散と言い, 電子が正孔を埋めることを再結合と言う.
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そして, 接合面には空乏層と呼ばれる電気的に中立で絶縁体の振舞いをする層が形成される\supercite{intro-electronic:pn-junction}.
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\begin{figure}[tbh]
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\centering
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\begin{minipage}[h]{0.3\linewidth}
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\centering
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\vspace{2.65em}
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\begin{tikzpicture}[scale=0.5]
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\filldraw[fill=blue!45] (0,0) rectangle ++(3,2);
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\filldraw[fill=blue!90] (3,0) rectangle ++(3,2);
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\draw (1.5,0) node[below] {p-Type};
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\draw (4.5,0) node[below] {n-Type};
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\pgfmathsetseed{7}
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\foreach \i in {1,2,3,4,5} {
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\draw
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let
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\n1 = {0.25 + random(1,10) * 3/15},
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\n2 = {0.125 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle] {+};
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};
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\pgfmathsetseed{8}
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\draw ({random(1,10) * 3/15}, rnd * 2) node[text=white,circle] {-};
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\draw ({random(1,10) * 3/15 + 3}, rnd * 2) node[text=white,circle] {+};
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\pgfmathsetseed{7}
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\foreach \i in {1,2,3,4,5} {
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\draw
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let
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\n1 = {5.75 - random(1,10) * 3/15},
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\n2 = {0.125 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle] {-};
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};
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\end{tikzpicture}
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\subcaption{Structure}
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\label{fig:pn-junction:structure}
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\end{minipage}
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\begin{minipage}[h]{0.3\linewidth}
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\centering
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\vspace{2.65em}
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\begin{tikzpicture}[scale=0.5]
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\filldraw[fill=blue!45] (0,0) rectangle ++(3,2);
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\filldraw[fill=blue!90] (3,0) rectangle ++(3,2);
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\draw (1.5,0) node[below] {p-Type};
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\draw (4.5,0) node[below] {n-Type};
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\pgfmathsetseed{7}
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\foreach \i in {1,2,3,4,5} {
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\draw
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let
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\n1 = {0.25 + random(1,10) * 3/15},
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\n2 = {0.125 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle](p\i) {+};
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};
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\pgfmathsetseed{8}
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\draw ({random(1,10) * 3/15}, rnd * 2) node[text=white,circle] {-};
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\draw ({random(1,10) * 3/15 + 3}, rnd * 2) node[text=white,circle] {+};
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\pgfmathsetseed{7}
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\foreach \i in {1,2,3,4,5} {
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\draw
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let
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\n1 = {5.75 - random(1,10) * 3/15},
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\n2 = {0.125 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle](n\i) {-};
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};
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\draw[-{Stealth},thick,draw=red!80] (p1.center) -- ++(0.75,0);
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\draw[-{Stealth},thick,draw=red!80] (p2.center) -- ++(0.75,0);
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\draw[-{Stealth},thick,draw=red!80] (p5.center) -- ++(0.75,0);
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\draw[-{Stealth},thick,draw=red!80] (n1.center) -- ++(-0.75,0);
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\draw[-{Stealth},thick,draw=red!80] (n2.center) -- ++(-0.75,0);
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\draw[-{Stealth},thick,draw=red!80] (n5.center) -- ++(-0.75,0);
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\end{tikzpicture}
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\subcaption{Diffusion}
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\label{fig:pn-junction:diffusion}
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\end{minipage}
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\begin{minipage}[h]{0.3\linewidth}
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\centering
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\begin{tikzpicture}[scale=0.5]
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\def\seed{13}
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\filldraw[fill=blue!45] (0,0) rectangle ++(2,2);
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\filldraw[fill=blue!90] (4,0) rectangle ++(2,2);
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\draw (2,0) rectangle ++(1,2);
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\draw (3,0) rectangle ++(1,2);
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\draw (1,0) node[below] {p-Type};
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\draw (5,0) node[below] {n-Type};
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\draw (3, 2.75) node[above](dl) {Depletion Layer};
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\draw[-{Stealth},thick] ($(dl.south) + (0,0.2)$) -- (3,2.2);
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\pgfmathsetseed{\seed}
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\foreach \i in {1,2} {
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\draw
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let
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\n1 = {0.25 + random(1,10) * 2/15},
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\n2 = {0.25 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle] {+};
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};
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\draw ({random(1,10) * 2/15}, rnd * 2) node[text=white,circle] {-};
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\draw ({random(1,10) * 2/10 + 3}, rnd * 2) node[text=white,circle] {+};
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\pgfmathsetseed{\seed}
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\foreach \i in {1,2} {
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\draw
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let
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\n1 = {5.75 - random(1,10) * 2/15},
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\n2 = {0.25 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle] {-};
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};
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\end{tikzpicture}
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\subcaption{Depletion Layer}
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\label{fig:pn-junction:depletion-layer}
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\end{minipage}
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\caption{pn-Junction}
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\label{fig:pn-junction}
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\end{figure}
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この接合に電圧を印加する時, 極性の違いで以下の状態となる:
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\begin{itemize}
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\item {電圧がn形半導体に電子を, p形半導体に正孔を供給し, 空乏層を消失させる(\cref{fig:pn-junction-voltage:forward})}
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\item {電圧がn形半導体の電子を, p形半導体の正孔を外側へ引き寄せ, 空乏層をさらに広げる(\cref{fig:pn-junction-voltage:reverse})}
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\end{itemize}
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そして, 電流はそれぞれの状態で導通, 遮断となる. これがダイオードの性質の一つである整流作用である\supercite{intro-electronic:diode}.
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\begin{figure}[tbh]
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\centering
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\begin{minipage}[h]{0.45\linewidth}
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\centering
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\begin{circuitikz}[scale=0.5]
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\filldraw[fill=blue!45] (0,0) rectangle ++(3,2);
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\filldraw[fill=blue!90] (3,0) rectangle ++(3,2);
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\draw (1.5,0) node[below] {p-Type};
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\draw (4.5,0) node[below] {n-Type};
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\pgfmathsetseed{7}
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\foreach \i in {1,2,3,4,5} {
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\draw
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let
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\n1 = {0.25 + random(1,10) * 3/15},
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\n2 = {0.125 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle](p\i) {+};
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\draw[-{Stealth},thick,draw=red!80] (p\i.center) -- ++(0.75,0);
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};
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\pgfmathsetseed{8}
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\draw ({random(1,10) * 3/15}, rnd * 2) node[text=white,circle] {-};
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\draw ({random(1,10) * 3/15 + 3}, rnd * 2) node[text=white,circle] {+};
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\pgfmathsetseed{7}
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\foreach \i in {1,2,3,4,5} {
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\draw
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let
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\n1 = {5.75 - random(1,10) * 3/15},
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\n2 = {0.125 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle](n\i) {-};
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\draw[-{Stealth},thick,draw=red!80] (n\i.center) -- ++(-0.75,0);
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};
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\draw (-2,-2) to [battery1, l_={$V_F$}, i_={$I_F$}] (8,-2);
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\draw (-2,-2) -- (-2,1) -- (0,1) node[above left] {$+$};
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\draw (8,-2) -- (8,1) -- (6,1) node[above right] {$-$};
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\end{circuitikz}
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\subcaption{Forward Voltage}
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\label{fig:pn-junction-voltage:forward}
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\end{minipage}
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\begin{minipage}[h]{0.45\linewidth}
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\centering
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\begin{circuitikz}[scale=0.5]
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\def\seed{13}
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\filldraw[fill=blue!45] (0,0) rectangle ++(1,2);
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\filldraw[fill=blue!90] (5,0) rectangle ++(1,2);
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\draw (1,0) rectangle ++(2,2);
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\draw (3,0) rectangle ++(2,2);
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\draw (0.5,0) node[below] {p-Type};
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\draw (5.5,0) node[below] {n-Type};
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\pgfmathsetseed{\seed}
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\foreach \i in {1,2} {
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\draw
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let
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\n1 = {0.2 + random(1,10) * 1/15},
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\n2 = {0.25 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle] {+};
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};
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\draw[-{Stealth},draw=red!80] (0.7, 1.4) node[text=white,circle] {-} -- ++(1,0);
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\draw[-{Stealth},draw=red!80] (5.4, 1.5) node[text=white,circle] {+} -- ++(-1,0);
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\pgfmathsetseed{\seed}
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\foreach \i in {1,2} {
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\draw
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let
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\n1 = {5.8 - random(1,10) * 1/15},
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\n2 = {0.25 + random(1,10) * 2/15}
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in
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(\n1, \n2) node[text=white,circle] {-};
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};
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\draw (8,-2) to [battery1,l={$V_R$}, i={$I_R \lll I_F$}] (-2,-2);
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\draw (-2,-2) -- (-2,1) -- (0,1) node[above left] {$-$};
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\draw (8,-2) -- (8,1) -- (6,1) node[above right] {$+$};
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\end{circuitikz}
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\subcaption{Reverse Voltage}
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\label{fig:pn-junction-voltage:reverse}
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\end{minipage}
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\caption{Applying Voltage across pn-Junction}
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\label{fig:pn-junction-voltage}
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\end{figure}
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ダイオードには極性があり, p形半導体の方をアノード, n形半導体の方をカソードと呼ぶ.
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これらダイオードは電流を流し始めるまでに一定電圧以上を掛ける必要がある. この電圧を順電圧と呼ぶ.
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一般的なシリコンダイオードの順電圧は0.6 V程度である.
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また, 順電圧に至るまで電流が流れない領域のことを不感領域と言う\supercite{intro-electronic:diode}.
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順電圧を増加させると順電流が急激に増加する, これがダイオードの非線形性である.
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半導体素子の多くは単純なオームの法則に従わない. 回路計算する際にはテブナンの定理などを駆使していく必要がある\supercite{intro-electronic:diode-circuit}.
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\begin{figure}[tbh]
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\centering
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\begin{circuitikz}
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\draw (0,0) node[above]{Anode} to [D*, o-o] ++(3,0) node[above]{Cathode};
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\end{circuitikz}
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\caption{Circuit Diagram of Diode}
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\label{fig:diode}
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\end{figure}
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\subsection{発光ダイオード}
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発光ダイオード(LED)とは, 順電圧を掛ける時に光を放つダイオードである.
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主に低電力・高効率な照明や表示灯に使用されている.
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光は電子と正孔が再結合し消滅する時に発生する. この明かるさは電流に比例する.
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LEDの順電圧はシリコンダイオードよりも高く, 2 V以上の物が多い\supercite{intro-electronic:led}.
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\begin{figure}[tbh]
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\centering
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\begin{circuitikz}
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\draw (0,0) node[above]{Anode} to [full led, o-o] ++(3,0) node[above]{Cathode};
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\end{circuitikz}
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\caption{Circuit Diagram of LED}
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\end{figure}
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