"Polychromator"-a Method for Studying the Selective Integral Photosensitivity of Semiconductor Materials and Devices

A new technique is proposed, verified, and described for measuring photosensitivity spectra of semiconductor materials and devices in the wavelength range of 200-4100 nm utilizing an innovative setup termed "Polychromator" with a system of cut-off optical filters that provide a sharp edge of the spectrum of radiation impinging on the sample. The measured value, referred to as selective integral photosensitivity (SIPhS), is calculated for the particular subbands of the spectrum taking into account the radiation power. Certain IR spectral characteristics, measured with a monochromator, are provided for comparison. It is shown that the presented "Polychromator" measurement data do not contradict these results, and in fact, complement them. The reliability of the method is demonstrated by three types of test photodiodes fabricated using three base materials: 1) B + ion-implanted n-Si; 2) InGaAs/InP; and 3) undoped AlGaN/GaN heterostructures. The selected materials and the devices made therefrom differ in the nature of photoresponse revealed in the various wavelength ranges. This allows for comprehensively describing the methodology. The information gained using this method as well as its advantages and ways of improving the setup are discussed.