Study On InP-based Near-infrared Device

Recent years,InP has become one of the hottest topics in semiconductor field.Three important InP based photoelectric devices are systematically studied in this article,including the In_0.53Ga_0.47As/InP Heterojunction Phototransistors?HPTs?with high internal gain,super-speed and low operation voltage;Al/MoO₃/p-InP Schottky Barrier Diodes?SBDs?with good rectifying behavior;and a InP substrate photodetector with In_0.66Ga_0.34As/InAs Superlattice?SL?electron barrier.Firstly,we present a back illuminated pnp In_0.53Ga_0.47As/InP HPTs along with a corresponding spectral response model,the spectral response model is developed from the solution of the steady state continuity equations that dominate the excess optically generated minority-carriers in the active regions of the HPTs with accurate boundary conditions.Calculated responsivity is in good agreement with the measured one for the incident radiation at 980 nm,1310 nm,and 1550 nm.Furthermore,the variation in the responsivity of the device with the base region width is analyzed.Secondly,the Al/MoO₃/p-InP MOS and Al/p-InP MS SBDs have been fabricated to confirm Schottky barrier heights?SBHs?enhancement by inserting an ultra thin oxide layer between the Al/p-InP MS contact.Current-voltage?I-V?and capacitance-voltage?C-V?measurements have been performed in the temperature range of 310-400 K.SBHs and ideality factor were calculated based on the theory of Thermionic Emission?TE?.It is found that,the SBHs for these two diodes have decreased with decreasing temperature while the ideality factor values have increased with decreasing temperature,obeying the barrier height Gaussian distribution model.By plotting modified Richardson plot,the Richardson constant of 66.16 and 59.07 A cm^-2 K^-2 for Al/MoO₃/p-InP MOS SBDs and Al/p-InP MS SBDs were obtained,respectively,which are both close to the theoretical value known for p-InP(60 A cm^-2 K^-2).Finally,a InP substrate photodetector with In_0.66Ga_0.34As/InAs SL electron barrier in the In_0.83Ga_0.17As absorption layer has been designed,where energy band engineering were employed by tailoring the carriers transport optionally,results show that the dark current was reduced dramatically.It was found that the period of SL has a remarkable influence on the properties of the photodetectors in the model established that the dark current density will suppressed significantly when the period of In_0.66Ga_0.34As/InAs SL is decreased,which has been interpretated by the electric field intensity of the structure.So,we can draw a conclusion that decreasing the In_0.66Ga_0.34As/InAs SL period is an effective method to suppress the dark current and improve the detectivity for the device.