Doping background

Very high growth rates and outstanding purity has been achieved using this technique. Growth rates between 15-50 m/hr and background doping in the low 10 ... 

The piezoelectric field induces charge at the heterojunction. Even mi unintentionally doped (with low background doping density) AlGaN/GaN heterostructure has a piezoelectric-induced sheet charge in the GaN channel, which is found by electrostatic analysis to be... 

Fig. 3.7. (a) Metal-insulator contact in thermal equilibrium (b) The contact under externally applied field, (c) electric field profile F(x) and hole density p(. ) under an applied bias of 10 V (d) J—V plot as given by Eq. (3.12). The thickness of the sample is 100 nm and a value of e is 3 and (e) The effect of background doping concentrations (1014, 10 and 10 cm-3) on the current. The doping dominated regions at low voltages are ohmic shown by the straight lines. 

Let the background doping concentration be no and let us assume that they are all ionized at the temperature of measurement. The concentration of existing holes due to background doping is also no. However their charge is compensated due to the ionized impurities. The total concentration of holes is p, the concentration of holes that contribute to the electric field is p - no. The Poisson equation (3.4) changes to,... 

The expression is useful for determining the background doping concentration 0 by measuring Vtr experimentally. The expression for Vjr is different for a solid that has traps. 

Han et al. [147] were interested in determining the built in potential in a-Si H p-i-n solar cells. They measured extensively the I-V characteristics of dark and illuminated solar cells. The dark characteristics are shown in Fig. 5.24(a). The symbols are the experimental data and the solid lines are the fits of SCLC theory. The theory agrees with the experimental data well except for small voltages. As discussed earlier the discrepancy at small voltages is either due to background doping or due to leakage currents. Since... 

Ion Implanted Resistors. If a substrate is doped with a layer of impurities opposite to that of the background doping, the resistivity is given by the total number, Ns> of the mobile carriers/cm2 and the mobility ... 

---