The frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the Au/polyvinyl alcohol (Ni, Zn-doped)/n-Si Schottky barrier diodes (SBDs) was investigated in the frequency range of 3 kHz-3 MHz at room temperature by considering series resistance (Rs) and interface states (Nss) effects. The C-V and G/ω-V characteristics confirm that the Rs and Nss are important parameters that strongly influence the electrical parameters of SBDs. The C-V plots show an intersection point (∼2.9 V) at low frequencies (f ≤ 30 kHz) and then take negative values, which is known as negative capacitance (NC) behavior. The negativity of the C increases with the decreasing frequency in the forward bias voltage region, and this decrement in the NC corresponds to the increment in the conductance. Also, the forward bias C-V plots show an anomalous peak in the voltage range of 1.55–1.9 V depending on the frequency such that the anomalous peaks shift toward positive voltage values with the incre...

The origin of anomalous peak and negative capacitance in the forward bias capacitance-voltage characteristics of Au/PVA/n-Si structures

The negative capacitance behavior in light-emitting diodes and laser diodes has been observed and characterized by using ac admittance–voltage method. Experimental results proved that the strong negative capacitance behavior is always accompanied by remarkable light emission. We confirmed that the negative capacitance is an effect of the junction instead of other behavior or measurement error. We presented a numerical calculation by solving one dimension continuity equation based on a simple diode model. The results show that the negative capacitance behavior in light-emitting diodes has great relation to injected carriers recombination in the active region of luminescence.

Negative capacitance in light-emitting devices

Frequency and voltage dependence of negative capacitance in Au/SiO2/n-GaAs structures

Precise ac electrical measurements as well as dc I‐V plots at forward bias have been used to characterize multi-quantum-well (MQW) laser diodes. Step offsets of apparent conductance, apparent capacitance, junction voltage, series resistance, and ideality factor at lasing threshold were observed. To compare the electrical characteristics of different diodes numerical simulations of the IdV∕dI‐I curve of the double-heterostructure (DH) laser were performed. We find that the conventional model used to explain this curve is not very satisfactory. Our simulations demonstrate that the junction voltage, series resistance, and ideality factor for both DH and MQW lasers exhibit the same sudden changes at threshold. Perhaps the electrical behavior near threshold for all laser diodes is very similar.

Simultaneous sudden changes of electrical behavior at the threshold in laser diodes

In this paper we present a model of impedance and modulation time constants for vertical-cavity surface-emitting lasers (VCSELs) operating above threshold current. A 3D numerical model of potential distribution in the device under a constant bias is used to determine resistances and capacitances of an appropriate equivalent circuit. The model has been verified by comparing the theoretical and measured impedance as a function of frequency Z(f). The measured Z(f) is determined from S 11 small signal modulation experiments. The comparison has been performed for frequencies up to 40 GHz and a wide range of above threshold currents, for two oxide-confined VCSELs of different aperture diameters. We obtained a very good quantitative agreement for frequencies up to about 15 GHz and qualitative agreement over the entire range of currents and frequencies.

https://iopscience.iop.org/article/10.1088/0022-3727/49/17/175104/pdf

Numerical model of capacitance in vertical-cavity surface-emitting lasers

Accurate forward electrical characteristics of multiquantum-well (MQW) lasers have been measured using ac admittance measurements together with dc I-V plot. The synchronous step offsets of apparent conductance, apparent capacitance, junction voltage, series resistance, and ideality factor at the onset of lasing were observed for the first time. With this effect, the lasing threshold can be deduced immediately by the LCR Meter. It is also found that the junction voltage jumps abruptly to a saturated value at the onset of lasing, and the starting and end points of jumping exactly correspond to the maximum of the second derivative of lasing power with respect to current and the kink point of the first derivative, respectively. All of the phenomena may help to verify and improve existing semiconductor laser models. In addition, negative capacitance effect in LDs was observed

C.Z. Lu

Papers

Sudden Change of Electrical Characteristics at Lasing Threshold of a Semiconductor Laser