Apple Inc. (NASDAQ:AAPL) last changed the iPhone’s display size to 4 inches from 3.5 inches way back in 2012, but rumor mills have picked up speed recently and are increasingly pointing to the possibility that the company is preparing for yet another hike in screen size this year for its iPhone 6, the presumed next-generation version of the handset. And, a set of internal company documents show why.

The documents, brought to light by the latest trial between Apple and Samsung Electronics Co. Ltd. (KRX:005935), provide significant insight into the California-based company's analysis of the future of the smartphone market, while also revealing that the iPhone’s growth is slowing and the company understands that the slowdown is because of its decision to keep the iPhone's screen size relatively constant while its competitors have continued to offer bigger smartphones to an increasingly demanding global market.

Documents released in court, which included slides from an April 2013 meeting about Apple’s plans for 2014, show the iPhone's growth rates have slowed quarter after quarter, and the main reason behind its decline is the growing demand for "less expensive & larger screen smartphones."

Apple-iPhone Apple admits that consumers want larger and cheaper phones. Photo: Re/code

The slides, posted by Re/code, also reveal a growing realization within Apple that “consumers want what we don't have,” and that the majority of growth in the smartphone market is coming from devices with screens bigger than 4 inches and a price tag under $300.

AppleiPhone Apple admits that "consumers want what we don't have." Photo: Re/code

The 16GB unlocked version of the current iPhone 5s, which features a 4-inch display, costs $649, while the 32GB and 64GB versions are priced at $749 and $849, respectively. The 16GB unlocked version of the iPhone 5c costs $549, while the 32GB version of the device is available for $649. In comparison, the 16GB unlocked version of Samsung's Galaxy S4 flagship phone is available for $429 on Amazon's portal. 

The leaked documents also suggest that Apple is aware of the latest consumer trends in the smartphone industry. And, if current rumors are to be believed, the company is working to address them with two iPhone 6 models with bigger displays that are expected to be launched later this year.

Although it is unlikely that Apple will bring the price down on its next-generation iPhone, the company could sell a bigger iPhone 6 at a premium while dropping the price of its current iPhone lineup to hit the sub-$300 price point, 9to5Mac reported.

Rumors have it that bigger iPhone 6 models could feature displays measuring 4.7 inches and 5.5 inches, with the smaller model expected to hit the market first. The 4.7-inch version of the iPhone 6 is expected to be released sometime in September or October, while the bigger-screen version is rumored to come later.