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This paper recommends the use of grasshopper optimization algorithm (GOA), a nature-inspired optimization algorithm, for optimizing switching-angle applied to cascaded H-bridge multilevel inverter (CHBMLI). Switching angles are selected based on the minimum value of the objective function formulated using the concept of selective harmonic minimization pulse width modulation (SHMPWM) technique. MATLAB/Simulink-PSIM dynamic co-simulation conducted on a 3-phase 9-level CHBMLI shows that the CHBMLI controlled using GOA derived switching-angle is able to respond to varying modulation index demand and synthesize an AC staircase output voltage waveform with the desired fundamental harmonic and minimized selected low-order harmonics. Compared to Newton Raphson (NR) technique, GOA is able to find optimum switching-angle solutions over a wider modulation index range. Compared to Genetic Algorithm (GA), GOA is able to find global minima with higher probability. The simulation results validate the performance of GOA for switching-angle calculation based on the concept of SHMPWM.

Multiplication and avalanche excess noise measurements have been undertaken on a series of AlInP homo-junction p-i-n and n-i-p diodes with $i$ region widths ranging from 0.04 to 0.89 $\mu \text{m}$ , using 442 and 460 nm wavelength light. Low dark currents of $^{\mathrm {-2}}$ at 95% of breakdown voltage were obtained in all the devices because of its wide bandgap and there was no tunneling dark current present even at high fields >1000 kV/cm. For a given multiplication factor, the excess noise decreased as the avalanche width decreased due to the dead-space effect. Using 460 nm wavelength light, measurements showed that a separate absorption multiplication avalanche photodiode with a nominal multiplication region width of 0.2 $\mu \text{m}$ had an effective $k$ (hole to electron ionization coefficient ratio) of $\sim 0.3$ .

A set of highly generalized electron-trajectory tracking equations are derived based on the fundamental of high field carrier transport and are employed in a Simple Monte Carlo model for gain and avalanche multiplication noise prediction in APDs with arbitrary electric field gradients. Using the model and assuming electron-only ionization, simulations are carried out on two one-sided abrupt np+ and n+p junctions with doping concentrations in the n and p regions set to 1.0×1018 cm-3 and the p+ and n+ regions set to infinity. Preliminary simulation results of gain, avalanche multiplication noise, and positions of electron ionizations obtained from the Simple Monte Carlo model employing the electron-trajectory tracking equations show excellent agreement with those obtained from the conventional Simple Monte Carlo model even though the one-sided abrupt np+ and n+p junctions are subjected to steep electric field gradient across the avalanche multiplication regions. These simulation results, and the positions o...

Avalanche photodiodes (APDs) with steep electric field gradients generally have low excess noise that arises from carrier multiplication within the internal gain of the devices, and the Monte Carlo (MC) method is among popular device simulation tools for such devices. However, there are few articles relating to carrier trajectory modeling in MC models for such devices. In this work, a set of electric-field-gradient-dependent carrier trajectory tracking equations are developed and used to update the positions of carriers along the path during Simple-band Monte Carlo (SMC) simulations of APDs with non-uniform electric fields. The mean gain and excess noise results obtained from the SMC model employing these equations show good agreement with the results reported for a series of silicon diodes, including a p+n diode with steep electric field gradients. These results confirm the validity and demonstrate the feasibility of the trajectory tracking equations applied in SMC models for simulating mean gain and exc...

Electron and hole multiplication characteristics have been measured on a series of Al0.52In0.48P p+-i-n+ and n+-i-p+ homojunction diodes with nominal avalanche region thicknesses ranging from 0.22 to 1.03 μm. From these, the electron and hole impact ionization coefficients are deduced over an electric-field range from 530 to 990 kV/cm. The results suggest that the electron ionization coefficient is larger than the hole ionization coefficient, particularly at lower electric fields. Extremely low dark currents were obtained, and there was no evidence of any tunneling dark current even at electric fields of approximately 1.0 MV/cm. From these ionization coefficients, we deduce that the breakdown voltage in Al0.52In0.48P is almost 2.5× greater than that of GaAs and 4.5× lower than that of GaN.

Al0.52In0.48P is the largest bandgap material in III-V non-nitride semiconductors that is lattice matched to a readily available substrate (GaAs). Having a bandgap narrower than that of GaN enables it to detect wavelengths around 480 nm. Such wavelengths have the best transmittance underwater and may be used as a carrier in underwater communication systems. We present an Al0.52In0.48P homo-junction Separate-Absorption-Multiplication-Avalanche-Photodiode (SAMAPD) as a high sensitivity detector for such an application. By increasing the neutral and space-charge region thicknesses, the peak response wavelength can be tuned to longer wavelengths with a narrower full-width-half-maximum (FWHM). The quantum efficiency of the detector reduces with FWHM and this is compensated by having an avalanche gain. At room temperature, the SAM-APD has a dark current of

The absorption properties of Al0.52In0.48P have been investigated near the fundamental absorption edge by measuring the photocurrent as a function of wavelength in a series of PIN and NIP diodes. Modelling of the photocurrent in these structures enables the absorption coefficients to be determined accurately over a wide dynamic range, which allows the direct and indirect band-gap to be determined.